Kernel Traffic #60 For 27 Mar 2000

Most of the people following your page probably do not realize that the "Capabilities" being added to Linux are a very poor substitute for true capabilities as implemented by systems like EROS.

The discussions at http://www.eros-os.org/faq/basics.html explain what a pure Capabilities model is. The past kernel discussion at http://www.linuxhq.de/kt/kt19990422_15.html#2 explains clearly why what is being added to Linux is a different beast all together.

I think that you should link back to that conversation to help clue in a few people...

Change	Author
Revert megaraid driver to 1.04 due to apparent corruption problems some firmware shows. This is a temporary state of affairs I hope, once Dell/AMI have a handle on which firmware and how to either fix it or refuse to boot on those firmwares then we can go back.	(me)
Acard scsi shared IRQ fix (hopefully) Folks with Acard stuff please test this one hard	(Acard, ported into newer driver by me)
Fix assorted network driver ioctl checks	(Mitchell Blank Jr)
Two small updates to the telephony API needed by other vendors	(me)
Fix bit masking error on IO port in I2O	(Deepak Saxena)
Work around spitfire errata 32 and 54 on Ultrasparc	(Dave Miller)
Work around Sparcstation 5 Swift MMU	(Dave Miller)
Fix SunQE problem with 32bit sparc	(Dave Miller)
Fix breakage of ISA support in SX driver and add EISA support	(Rogier Wolff)
Arlan fixes (but not 4500 for 2.2.15)	(Elmer Joandi)
Fix EXPERIMENTAL checking in 2.2.15pre	(Paul Vojta)
Update AIC7xxx driver to rev 5.1.28	(Doug Ledford)
Simple (ie not strictly correct) fix for the cisco 3600 syncppp problem [Proper fix for 2.2.16 I think]	(Madarasz Gergely)
Zero the sin_zero part of sockaddr_in	(Frank van Maarseveen)
Correct erase handling in 16 colour text	(Jon Mitchell)
Fix typo in videodev.h	(fjolliton)
Another small ultrasparc errata fix	(Dave Miller)
Semaphore deadlock fix	(Christoph Rohland)
Further SX fixes	(Rogier Wolff)
SKTR driver fixes	(Christoph Goos)
Further small 3ware fix	(Adam Radford)
Up the default number of module loadable scsi disks to 16	(me)
Wan config typo fix	(Dave Jones)
Sparc blackbird errata fixes	(Dave Miller)
Wanpipe needs inet	(Arjan van de Ven)
Revert cursor/bh lock patch (breaks Alpha)	(me)
Fix ext2 dir race	(Al Viro)

OOM testing people keep complaining to me that their klogd dies in 2.2.15pre13 (where my code got backed out).

Do you have plans of integrating OOM handling code or is my time better spent hacking other things?

I just made a 2.3.51 release, and the next kernel will be the first of the pre-2.4.x kernels. That does NOT mean that I'll apply a lot of last-minute patches: it only means that I'll let 2.3.51 be out there over the weekend to hear about any embarrassing problems so that we can start the pre-2.4 series without the truly stupid stuff.

There's some NFSv3 and other stuff pending, but those who have pending stuff should all know who they are, and for the rest it's just time to say nice try, see you in 2.5.x.

The pre-2.4.x series will probably go on for a while, but these are the "bug fixes only" trees. These are also the "I hope a lot of people test them" trees, because without testing we'll never get to the eventual goal, which is a good and stable 2.4.x in the reasonably near future.

No. The controller has over-voltage protection, so it just means that it won't work.

The problem is actually due to a unlucky interface between the low-level slot driver and the card services layer: there's a flag that says "I'm a 3V card", but there is NOT a flag that says "I'm a 5V card". So what happened here is that

• the cardbus controller did not report any voltages at all.
• the low-level driver thus did not set the 3V flag.
• cardservices thought that "not 3V" == "5V"
• it didn't work.

The fix in 2.3.51 is for the low-level driver to notice that neither the 5V nor the 3V flags were set, and if that happens it will try to force a re-sense of the card.

I've seen this with the TI1225, and it does not happen with my Ricoh controller in my Sony VAIO that I did most of the development on. So I think it's actually a buglet in the TI core.

You are more optimisic than me on time scales. I have to agree that making 2.4pre the freeze and fix stuff makes sense. Its a clear line.

I assume the raid stuff is in 'pending'?

From my side I'll push you 2.2.15pre and the remaining unmerged drivers (COMX) this weekend. That makes sure 2.4pre is in sync with 2.2.15 fix ups. I'll also update the jobs list

There is a big i2o block driver update pending from Intel. If its sane I'd like to get it in, if its not sane then I need to get bits of it in fixed up to handle geometry and other compatibility issues. This wont stray outside drivers/i2o

Umm Apache 2.0, Xfree 4.0 and 2.4pre all in a week. This is going to make the ftp archives suffer 8)

I can add it during 2.4.x - adding new drivers is not a problem, the same way we have added new drivers to 2.2.x.

But at this point I'd prefer to not get it for the pre-2.4.x series, just to make the patches smaller and hopefully bug-fixes only.

The only special case would be if somebody comes out with a driver that is for something =SO= popular that I think everybody will want it in 2.4.0 and not have to wait. I can't think of any such thing off-hand, but maybe a softmodem driver would count for psychological reasons or something like that.

Ahhah!

This is another change in 2.3.x behaviour: it is a POSIX requirement that I don't particularly like, but there you have it. Any access past the last page of a file should give a SIGBUS. Previous Linux behaviour was to just map in a zero page.

I will leave the SIGBUS behaviour, andif this is the only program that breaks due to new POSIX conformance, I will consider us very lucky indeed.

Finges crossed. If some other major package breaks we will probably have to forget that particular conformance detail..

We now have a working port of reiserfs for 2.3.49, and I am not sure whether you consider us pending. Can reiserfs get in? Putting us in as an experimental file system until we are accepted by the community as known stable is just fine. Our 2.2 version seems to be accepted by the users on our reiserfs mailing list as stable.

We'll port it to the new 2.3.51 starting immediately, the 2.3.49 version will hit our webserver in a few hours.

Sorry we tweaked longer than we should have, and created inconvenience for you.

ReiserFS for 2.3.49 is now available for testing, comments, and review. You can get the code from:

ftp://ftp.devlinux.com/pub/namesys/2.3-beta/linux-2.3.49-reiserfs-3.6.1-patch.gz

This is beta code, and support for the disk format in our code for the 2.2. kernel is turned off right now (more on that below).

We realize this isn't as useful as a 2.3.51 patch, which we are working on right now. Looking through the VFS changes in 2.3.51, I don't anticipate problems porting up, but I wanted to get this code out just in case. Look for the 2.3.51 patch Sunday night, perhaps on Monday if things get really ugly.

I've added a new call in the super_operations struct, called read_inode2. This is a kludge to pass all 64 bits reiserfs_read_inode needs to find something on disk. As I understand things, the VFS changes in progress to make knfsd happy will allow us to get rid of the read_inode2 hack.

Big differences from our 2.2 code:

We've changed our stat data and the keys used to find objects in the tree. We have code in place to support the old disk format, but we concentrated on testing the new format first, so that compatibility code is disabled right now.

You won't be able to mount a 2.2 formatted disk with this patch. The new format was designed around making old format support easy, we are committed to providing it once we are convinced the new code is solid.

The horrible things we did to linux/fs/buffer.c have been removed.

64 bit file offsets, and disk format should be safe for use on alphas. The alpha port is not finished, but it is at least possible now. If you are interested in helping, please let us know.

page cache integration resulted in big changes in when we pack file tails. Files with tails will be slower than they were in the 2.2 code, until we make better use of the address space operations.

What still needs to be done:

2.3.51 port, more testing.

new format support ported back to 2.2.X kernels. This comes after testing the old format support in 2.3.X kernels, so it should take at least a month.

fsck needs to be ported into the new format, so does the resizer.

memory pressure hooks would be very useful. We have a hard to reproduce deadlock under very high swap load, where kswapd ends up waiting on the log while trying to flush inodes to disk. I have a work around planned (all in the journal code), it won't take long to code, but it will take a few days to test right.

Code cleanup (esp. the journal API)

journal tuning code, including per filesystem journal sizes. I've been promising this forever. Now that our 2.3 changes are almost done, I can finally think about adding it. The super has all the fields need to make this happen already.

A few misc bug fixes from the 2.2.X code need to be ported in.

Again, this is beta code, please don't put data on it you care about yet.

We don't yet have a set of valid benchmarks. I can generally say that I don't have confidence in the benchmark performance of this code, there are too many tweaks not yet done, and our goal for Monday is a port to 2.3.51 that does not crash. I hope Linus will put this port in as an experimental filesystem, and then a bit later we'll be able to tell him the performance merits making it a more than experimental use FS.

We have some tail packing algorithms new to 2.3 that are worse in some benchmarks than the 2.2 code. This will be fixed after more time for tweaking (or going back to the old algorithms) passes.

It has long been an architectural weakness of ReiserFS that we allocate block numbers to buffers as we need each buffer. We knew that we should cure this by doing either pre-allocation of blocknrs as ext2 does (meaning allocate many blocks at a time, and then keep them reserved for that file until file close), or allocating block numbers on dirty buffer/page flush as XFS does. It is for sure the case that our current practice of allocating blocks as we need new buffers to write into is a bad architecture. Yura wrote some pre-allocation code that improved our performance by as much as 4x in some benchmarks, but I discouraged it because I prefer allocate on flush. This decision is hurting us at the moment. Pre-allocation is much easier to code (and already written by Yura for an older version), allocate on flush is the right answer long-term. Zam has been working on allocate on flush for about 6 weeks, but it is not ready yet. I think we will have Yura throw in his pre-allocation code until the allocate on flush code is completed. I hypothesize (not enough data yet to consider it an observation) that having good SMP in VFS makes writes more evenly interleaved using our current block allocation bad architecture, and more evenly interleaved is bad for performance.

There is also unfinished work to decrease the lock granularity throughout reiserfs. We don't yet know how much effect that has, but it surely has some.

So, in summary, 2.3.51 ~Monday, not sure how many days for pre-allocation but not a lot. We really need that allocate on flush code and a few more tweaks in various places before we can start smiling at our benchmarks and taking weekends off again, but until then I hope we will at least be admissible as an experimental FS. Everyone is working quite hard.

Please, start with removing the crud from your code. It's the same picture all over the place. Excuse me, it's kinda hard to consider the patch seriously when it's bloody obvious that nobody cared to check what happened with VFS during the last two years unless the changes broke compile. I _know_ that not all changes of rules were detectable that way. And I wouldn't bet a dime that you got them right (especially since one example of the contrary can be found two paragraphs above). It's not like that was a 2.3-only thing - your code is incorrect for 2.2 since the February/March 1999...

When this sort of crap will be cleaned up and code really audited and _understood_ by your team - fine, there will be a point in talking about this animal more seriously. Right now you are pushing the patch with large chunks of code you've copied years ago and had not maintained since then. Sorry, but it's not a good idea.

Ok, yes, there are places like this, and clearly, they need to go away. We are subscribed to fs-devel, and we are making a real effort to stay more up to date on all the kernel changes (yes, we are on fs-devel). We should have been fixing the problems you described earlier, but it just didn't get done.

I'm sending a patch out in a few hours that will have bug fixes, and a port to 2.3.51. It won't have the cleanup you describe, I'll start on that on Monday.

Many thanks for you comments and review.

Alexander, if you tell us what you want done when making VFS changes we will do it for you. You don't need to take the responsibility for working on reiserfs code you dislike if you don't want it. Truly. You can go on using ext2 and telling all your friends to use ext2, and when you change VFS just let us know.

On the other hand, I am very happy to get flames from you which are specific in what they complain of. It is bedtime for me now, but I am cc'ing the below to Vladimir and Alexei in Russia. It would be nice if you would frame your remarks in the form of: you do A, B is the right thing, or A is bad because of such and such, rather than you do A, you are clueless.

The first forms lead to a faster fix. If fix is your objective.

Hans, I think Alexander has told us exactly what he wants done. He wants us to audit our entire VFS interface, and make sure that we are dealing with boundary conditions, special cases, and normal cases the same way the existing linux filesystems are. I don't think we need a list from him of the broken segments, we should be able to find them on our own. This is not an unreasonable request from him, and we should not treat it as one.

Once we fix what we can find, we'll send the patch in again, and hopefully the people on linux-kernel and fs-devel audit the code again. This is exactly the kind of feedback I was hoping for, and it is appreciated.

Alex Viro's concerns are not about whether reiserfs passes stress tests. They're about subtle, and not too subtle deadlock, livelock and race conditions, and long term maintainability.

As soon as an fs goes into the kernel, even marked as "experimental", then every time Alex modifies VFS he has to look at all the kernel filesystems and verify that his VFS changes are valid. Sometimes this means he has to change the filesystems themselves. Also Alex Viro is not the only person who does this.

That can only be done if every fs in a single kernel release makes the same set of assumptions about what to test, what locks are held for different functions, when to call iput, dput, d_delete and d_move, whether to check S_ISDIR etc.

Currently reiserfs does not make the same assumptions as the current kernel filesystems. So it cannot be included even though it passes its own stress tests: including reiserfs would create too much work for people modifying and auditing VFS.

Sure you could keep a note with it saying "this filesystem is not maintained in the kernel". But then there's no point including it in the kernel tarball.

Now, now, don't be too harsh on the resierfs guys.

Do we suddenly expect code to be bug-free before inclusion into the kernel?

For rather obvious PR reasons I'd love to say "yes, we have a journalling filesystem these days" as part of the 2.4.x release stuff, so it does fall under the "drivers so cool that they might make it into 2.4.x". I don't think I want to see the read_inode() changes, though, that's just too ugly. I may like the PR angle of reiserfs, but that doesn't mean that I'd forget about things like these completely.

But it looks to me as if the read_inode thing plus a few cleanups in raiserfs to take into account that the VFS layer does more these days would certainly make it a candidate for inclusion. Maybe not 2.4.0, but during 2.4.x. Don't be so down on the guys, there are people who really like actively using raiserfs..

OK, let me summarize my position on that:

1. namespace-related methods _must_ be cleaned up. I definitely can just rip the extra checks out of the thing, but there are questions about correctness of said action. _If_ that was just the case of "replay all global changes that happened during last two years" I would be certainly PO'd but I would do it. However, some of those places do funny things with checks for ->i_count and friends. They may be harmless atavisms. They may be actual bugs. And they may be band-aids that cover real problems 99% of time. I don't want any responsibility for that stuff - analysis of reiserfs wrt races will involve going through the guts of their code and that's about 200Kb of stuff to read. IMO that's work for the reiserfs authors.
2. some things are obvious bugs and should be fixed both in 2.2 and 2.3 - e.g. d_move() in rename() is _wrong_ since 2.2.<early>.
3. having ~30Kb of unmaintained code in the patch is Bad Thing(tm). What about the rest? Obviously journalling code _is_ maintained (at least I _seriously_ hope that it is). Ditto for the allocation stuff, but here there may be need to account for big lock changes. And I would be much happier if somebody looked through ->truncate() searching for races. Andrea?
4. could you please convert symlink.c to pagecache? BTW, that would kill ugly REISERFS_KERNEL_MEM/REISERFS_USER_MEM stuff.
5. personally to Hans: please, _please_, lose references to Plan 9 namespaces in the documentation. Trust me, they are _NOT_ what you think they are (at least according to what you had written). It wouldn't be related to patch, but you are bringing the URL of that text into the tree. I'm 100% serious - those references may be good for marketing, but they'll make us a laughing stock for everyone who knows what Plan 9 namespaces are about. Hint: namespaces are _not_ about "everything can be viewed as filesystem". It's pure VFS thing and _nothing_ in your patch touches even remotely related areas.

1. In Progress
1. Merge the network fixes (DaveM)
2. Merge 2.2.13/14 changes (Alan, all done barring COMX and Sk98)
3. Get RAID 0.90 in (Ingo)
2. Fix Exists But Isnt Merged
1. Signals leak kernel memory (security) [JJ has fixes]
2. msync fails on NFS [Wrong return]
3. Semaphore races
4. Sempahore memory leak
5. Exploitable leak in file locking [Lock limit needed]
3. To Do
1. Restore O_SYNC functionality
2. Fix eth= command line
3. vmalloc(GFP_DMA) is needed for DMA drivers
4. VM needs rebalancing
5. Fix SPX socket code
6. put_user appears to be broken for i386 machines
7. Fix module remove race bug
8. Test other file systems on write
9. Directory race fix for UFS
10. Audit all char and block drivers to ensure they are safe with the 2.3 locking - a lot of them are not especially on the open() path.
11. Stick lock_kernel() calls around driver with issues to hard to fix nicely for 2.4 itself
4. To Do But Non Showstopper
1. Make syncppp use new ppp code
2. Finish 64bit vfs merges (lockf64 and friends missing)
3. NCR5380 isnt smp safe
4. DMFE is not SMP safe
5. ACPI hangs on boot for some systems
6. Get the Emu10K merged
7. Finish I2O merge
8. Go through as 2.4pre kicks in and figure what we should mark obsolete for the final 2.4
9. Per Process rtsigio limit
5. Probably Post 2.4
1. per super block write_super needs an async flag
2. addres_space needs a VM pressure/flush callback
3. per file_op rw_kiovec
4. enhanced disk statistics
6. To Check
1. Truncate races (Debian apt shows it nicely) [done ?]
2. Elevator and block handling queue change errors are all sorted
3. Check O_APPEND atomicity bug fixing is complete
4. Incredibly slow loopback tcp bug
5. Finish softnet driver port over and cleanups
6. Page cache high on PAE36 boxes is very slow, maybe disable ?
7. Protection on isize (sct)
8. Mikulas claims we need to fix the getblk/mark_buffer_uptodate thing for 2.3.x as well
9. Fbcon races
10. Fix all remaining PCI code to use new resources and enable_Device
11. VFS?VM - mmap/write deadlock
12. initrd is bust
13. rw sempahores on page faults (mmap_sem)
14. kiobuf seperate lock functions/bounce/page_address fixes
15. Fix routing by fwmark
16. Some FB drivers check the A000 area and find it busy then bomb out
17. NTFS needs updating/binning or something
18. rw semaphores on inodes to fix read/truncate races ?
19. Not all device drivers are safe now the write inode lock isnt taken on write
20. File locking needs checking for races
21. Multiwrite IDE breaks on a disk error
22. AFFS doesn't work on current page cache

Actually, all of the core netfilter support is merged.

The only thing left are the modules themselves, and that should be as simple as adding a new driver so in theory it could even occur during 2.4.x if needed.

I didn't finish the fbdev API changes. Its better but not perfect. You will see. I sent a patch to Geert to look over before he sends it to linus that updates vfb.c to show how a 2.4.X driver should be written. As for races. Its still not really multihead friendly. Neither is the console code as several of us with multihead system discover. SMP and multihead and console system don't mix :( The con2fb mapping is just a mess. Things like fbcon=map:0110 bombs if you don't have a second video card. Their is no way to fix this. Its a chicken and egg problem. fbcon_setup is called before fbmem_init so you can't do any sanity checking. The con2fb mapping stuff is just pure crap. Its just a pure hack to get multihead somewhat working. I hate it and can't wait to see it removed in 2.5.X.

The second problem is vgacon and fbcon. Until this last kernel you can boot vgacon and then inmod a fbdev driver and then fbcon would take over. Now the problem is most video card when they go from VGA mode to a non VGA mode can NOT go back to VGA mode. So if you go to rmmod the fbdev driver you are fubar. I just made a patch that changes the config.in files to have it so you either have to choose fbcon or vgacon. Its one or the other. This brings me to another question. Can prom console run at the same time as the framebuffers on a sparc station ? Same for some of the SGI stations. Can a newport console also run at the same time as a framebuffer console. This way my patch can ensure you can select between fbcon or some other console type.

1. In Progress
1. Merge the network fixes (DaveM)
2. Merge 2.2.15 changes (Alan)
3. Get RAID 0.90 in (Ingo)
2. Fix Exists But Isnt Merged
1. Signals leak kernel memory (security)
2. msync fails on NFS
3. Semaphore races
4. Sempahore memory leak
5. Exploitable leak in file locking
3. To Do
1. Restore O_SYNC functionality
2. Fix eth= command line
3. vmalloc(GFP_DMA) is needed for DMA drivers
4. VM needs rebalancing
5. Fix SPX socket code
6. put_user appears to be broken for i386 machines
7. Fix module remove race bug
8. Test other file systems on write
9. Directory race fix for UFS
10. Audit all char and block drivers to ensure they are safe with the 2.3 locking - a lot of them are not especially on the open() path.
11. Stick lock_kernel() calls around driver with issues to hard to fix nicely for 2.4 itself
12. PCMCIA/Cardbus hangs, IRQ problems, Keyboard/mouse problem (related ?)
13. Tulip hang on rmmod
14. Use PCI DMA by default in IDE is unsafe (must not do so on via VPx x<3)
15. Use PCI DMA 'lost interrupt' problem with some hw [which ?]
4. To Do But Non Showstopper
1. Make syncppp use new ppp code
2. Finish 64bit vfs merges (lockf64 and friends missing)
3. NCR5380 isnt smp safe
4. DMFE is not SMP safe
5. ACPI hangs on boot for some systems
6. Get the Emu10K merged
7. Finish I2O merge
8. Go through as 2.4pre kicks in and figure what we should mark obsolete for the final 2.4
9. Per Process rtsigio limit
10. Boot hangs on a range of Dell docking stations (Latitude)
11. Port SGI VisWS to 2.3.x or mark obsolete
12. S/390 Merge
13. HFS is still broken
14. iget abuse in knfsd
15. Mark NTFS as obsolete
16. via rhine oopses under load (softnet ?)
17. Symbol clashes and other mess from _three_ copies of zlib!
18. Paride seems to need fixes for the block changes yet
19. PIII FXSAVE/FXRESTORE support
5. Compatibility Errors
1. Shared memory changes change the API breaking applications (eg gimp)
6. Probably Post 2.4
1. per super block write_super needs an async flag
2. addres_space needs a VM pressure/flush callback
3. per file_op rw_kiovec
4. enhanced disk statistics
5. AFFS fixups
6. UMSDOS fixups resync
7. To Check
1. Truncate races (Debian apt shows it nicely) [done ? - all but Coda]
2. Elevator and block handling queue change errors are all sorted
3. Check O_APPEND atomicity bug fixing is complete
4. Incredibly slow loopback tcp bug
5. Make sure all drivers return 1 from their __setup functions
6. Finish softnet driver port over and cleanups
7. Page cache high on PAE36 boxes is very slow, maybe disable ?
8. Protection on isize (sct) [Al Viro mostly done]
9. Mikulas claims we need to fix the getblk/mark_buffer_uptodate thing for 2.3.x as well
10. Network block device seems broken by block device changes
11. Fbcon races
12. Fix all remaining PCI code to use new resources and enable_Device
13. VFS?VM - mmap/write deadlock
14. initrd is bust
15. rw sempahores on page faults (mmap_sem)
16. kiobuf seperate lock functions/bounce/page_address fixes
17. Fix routing by fwmark
18. Some FB drivers check the A000 area and find it busy then bomb out
19. rw semaphores on inodes to fix read/truncate races ? [Probably fixed]
20. Not all device drivers are safe now the write inode lock isnt taken on write
21. File locking needs checking for races
22. Multiwrite IDE breaks on a disk error
23. AFFS doesn't work on current page cache

Documentation doesn't a feature make. It seems odd that the kernel would not know where a filesystem is mounted. The kernel, more than anything else, ought to be aware of filesystem mount points.

BTW, /var/shm is a bad default. Stuff like this should be right on the root because /var may be a separate filesystem that gets mounted after the system already needs shared memory. (it would be even better to let this filesystem hang loose, active but not part of the normal tree at all)

No one expects anything from you and has not for a long time. If you wanted to actually WORK on the drivers, rather than just complain, then I'm sure many people including myself would find that work very valuable.

It is unarguable that you have more experience with these net drivers, but when was the last time you submitted a patch to Linus? Two years ago? Three? More?

I never claimed to be perfect but at least I am trying to fix some of the the bit-rotten, UNMAINTAINED net driver code currently in the kernel.

Finally, only the Tulip and RTL-8139 drivers are maintained by me. It takes a two-second grep of the MAINTAINERS file to discover this fact. Other drivers are still unmaintained, except when I get spare time to hack on them. (or when others send me patches for them)

David, pipe down.

You seem to like the approach Donald has taken. But take it from me, it DOES NOT WORK.

The problem is that maintaining the drivers in their own small universe means that only those people who follow the driver development will ever even test them. Which means that people for whom the old drivers are broken are basically the only ones testing the new drivers - and when a new driver is finally integrated into the base kernel it won't work for a lot of people that had a perfectly working driver in the old version.

And don't even bother telling me it doesn't happen. It happened to _me_ more than once. I decided that I should try to fetch Donalds latest and greatest _despite_ the fact that he hadn't even bothered to send it to me or to Alan, and it simply didn't work on the very basic hardware that I had.

I fixed the tulip driver at least twice to work with the media detection, and sent Donald email about what I had done and why (why: without those fixes it would notever get a link on the machine that I used). I don't know if my fixes ever actually made it into Donalds version, because after the second time I just stopped bothering trying to re-fix the same thing, and I never updated his driver again.

In contrast, what Jeff and others have done have been of the type where immediately when a fix is made, it is released. Which means that if there are problems with it, people who follow new kernel releases will know. Immediately. Not in a few months time when the next "driver release" happens.

This is what Jeff means with "closed source". Yes, the sources are there. Yes, they get released every once in a while. But Donald doesn't let people _participate_. He thinks he is the only one who should actually touch the driver, and then he gets very upset when things change and others fix up "his" drivers to take into account the fact that the interfaces changed.

I accept patches from anybody. I accept patches from people other than Jeff. If somebody sends me a bugfix for a driver, and it is so obvious that even I can tell that it must be better than the current code, I will apply it. Obviously, in many cases I cannot make a good judgement (because I don't know the hardware or other issues well enough), and that is when having a maintainer is important.

If anybody thinks that being the maintainer equals being in 100% control, then I don't think they have understood the TRUE meaning of Open Source. Open source is about letting go of complete control. Accept the fact that other people are wonderful resources to fixing problems, and let them help you.

It's about accepting the fact that open source means that interfaces will change. Not whining about it. And when somebody else steps forward that does a better job of maintaining a driver, accept it gracefully.

Donald's development is not open AT ALL. Read Donald's own description of how he developed the 2.3 network drivers and interface (pci-netif). He disappears for many months, creates a design without interfacing with kernel developers, and then appears again with a code drop.

It is classic cathedral style of development. Read Eric Raymond's paper on why the bazaar method is far, far superior. The Linux kernel is the bazaar method, and this is the central conflict which forced the kernel and Donald drivers to diverge.

Yes, the end result of Donald's work is open source, but his development is not open at all. And therein lies the problem [which existed far longer than I have been hacking on the net drivers...]

A quick search of the two very active Tulip mailing lists reveals that you have contributed nothing until this year. Apparently you were not even a subscriber until then, and know nothing about the very open way development has been done. Yet you willing throw around pejorative phrases like "cathedral style" -- a hot button in this community.

For those not interested what superficially appears to be a kernel power grab, there are issue underlying all of what appears to be a personal conflict.

1. Should the kernel source code interfaces, for well-understood interfaces, be stable? (We are solidly committed not having a binary interface, so bringing that up is a red herring.)
2. Given that development kernels are frequently unstable in some unexpected way, is is reasonable force testing of driver changes combined with unknown other changes?
3. Given that the kernel continues to exponentially increasing in size, should all development go through the latest development kernel?

I feel the network driver interface from 1.2.* through 2.2.* is the cleanest interface in the kernel. It's possible to add most new drivers to the kernel without modifying or recompiling the kernel source. I like to think that I influenced the clean design.

Compare that to the filesystem code, which requires that the kernel be reconfigured and recompiled if you wish to add a new filesystem. Or a new block driver, where there is a similar situation with block.h. Both the VFS layer and the block driver interface should be very well understood, but the nicely designed interfaces were quickly corrupted with ugly hacks.

I think the continued viability of a monolithic, single-point kernel source tree should be questioned. The average *compressed* patch size for the 51 kernel patches since 2.3.1 is over 346KB, totaling just under 18MB. When uncompressed, that's over 1MB per patch, far more than it's possible for anyone to reasonably review.

The usual justification for this scale of change is that only the developers should be using the development source tree. But the "official" advice to anyone with device problems, frequently repeated on the kernel mailing list, is to run the latest development kernel.

You're basically the only one thinking so.

The fairly recent changes in 2.3.x (the so-called "softnet" changes) are just incredibly more readable and robust than the old crap was that I don't see your point at ALL.

Just about every single network driver out there was SERIOUSLY broken wrt SMP and locking. I know, I had fixed many of them. The games the drives played with timeouts, "dev->interrupt", "dev->tbusy" etc were just incredibly baroque, and had absolutely NOTHING to do with "clean".

All of that crap is gone, and it was much overdue.

And it required every single networking driver to change. Tough. But that's the advantage of open source - in a closed source binary interface world we would have been basically unable to clean things up. We would have had to maintain some ridiculous backwards compatibility layer, making drivers and networking harder to understand.

The PCI layer changes are similar. Yes, we basically got rid of the old code that used to have "slot/fn" arguments to the PCI access functions. Instead, the functions got cleaned up, and you have to use "struct pci_device" instead, forcing drivers to be a bit more structured. Changes.

You seem to think that changes are bad. I disagree. I think a cleaner interface is worth just about ANY changes.

There is a reason for that for those dates, which you should have picked up on. That was when the driver development issue last came up, and I was thoroughly flamed for separate driver development lists, especially by Jeff. I was told that my contributions were no longer needed.

I decided to take a few month break from my driver update schedule, which was taking up most of my waking hours, to work on Scyld and the Beowulf software. I provide driver updates to clients that value them and write new drivers, but left the kernel development merges to those that obviously wanted control of them.

Trace back to the beginning of the current thread: this round of finger pointing was started because there are driver bugs that haven't been addressed, and 2.4 is about to come out.

It must have seemed like a good idea in Autumn '99, when the kernel was "just about to be frozen" in preparation for late-'99 2.4 release, and money was pouring into anything with "Linux" in the name, to believe that my Ethernet driver development could be better done elsewhere. There were many companies that could suddenly see that PR value in contributing to the kernel. And certainly there are developers that want to see everything brought under the central planning of the linux-kernel list. But replacing my efforts is perhaps not as easy as it first appears. Nonetheless, the decision was made months ago, and it would be very difficult to reverse it now.

Oh good grief, save the conspiracies for X-Files.

I won't speak for the motivations of others, but for me the 2.3.x kernel net drivers weren't getting updated, so I decided to play a small part in correcting that situation.

This has nothing to do with money, or control. Just broken drivers.

I'm in the increasingly untenable position of being expected to maintain drivers for the current and older kernels, but not having any influence over the new development exactly because of that backwards compatibility. It's no fun being responsible for just the old versions, especially after I did years of unpaid development work.

There were many interface changes added incrementally in the 2.3 kernels. Some with added without consideration of, or even in opposition to, cross-version compatibility. And few of those interface changes were designed, as opposed to just hacked in. When I proposed an new PCI detection interface I wrote a skeleton driver, converted several of my drivers, demonstrated that it worked with several hardware classes and wrote a usage guide. But the few day hack was added because the patches were incremental (even if misdesigned and broken).

Donald, that's not true, and you know it.

Neither I nor anybody else has expected you to maintain the drivers for quite a long time now - you just didn't seem to have the interest, and a lot of people have acknowledged that. That is why there ARE new maintainers for things like tulip and eepro100, whether you like it or not.

You did not lose influence of the drivers because you want to maintain backwards compatibility. You lost influence over the drivers simply because you never bothered to send in your changes. Don't start blaming anybody else.

You were more interested in making sure your drivers worked with old kernels than you were in making sure they worked with new ones. And now you're surprised that they are only used with old kernels? I don't see why.

I've had this problem before, and I don't like it.

I've worked on projects where the above happened, and it turned out that people ended up doing extra work just to make sure that the asserts were "right", instead of realizing that the thing that the assert "documented" was no longer worth maintaining.

I donot like asserts. I like temporary debugging aides, and I like them just as long as they are _seen_ as temporary debugging aides.

99% of all asserts I've ever seen have been a complete waste of time. They were useful when the code was written, because the code was buggy (or more often the code was not buggy, but all the "surrounding" code that depended on that piece of functionality had not been updated to new semantics). But they become either a liability or just worthless over time.

That's just my opinion, of course. I know that my views on debugging are pretty much scoffed at by a lot of people: I don't like debuggers either (for somewhat similar reasons - my strongly held personal belief is that debuggers tend to cause the _symptoms_ to be fixed rather than the actual underlying bugs that you fix when you think about the problem on a source level).

This is why I like BUG(). Not because it is any different from "assert()" in any real sense, but because it does not have the psychological mindset associated to it that "assert()" has..

There are only two problems with your thesis:

1. The check, although it is quite time consuming, only checks the bitmaps blocks to see if they match with the superblock group descriptors. On filesystems with 4k blocks, this means that you only catch errors that occur in 0.009% of the filesystem. (On filesystems with 1k blocks, you're cecking 0.03% of the filesystem --- in both cases, it's well less than a tenth of a percent.) Granted, the bitmap blocks get written a lot, but it still means that a large number of potential disk corruptions might not get noticed by the check.
2. If there are problems, the kernel simply prints a warning. Many of the non-experienced users are likely to not notice or ignore the warning messages which appear at boot-time anyway.
3. If someone *really* wants to do a potentially time-consuming minimalistic check, I can add it to e2fsck (it's basically means skipping passes 1 through 4 and only doing pass #5), but quite frankly, I'm still not convinced its worth the cost/benefit ratio. Still, people who are really paranoid could use this if they really want.