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Kernel Traffic #263 For 14�Jun�2004

By Zack Brown

Table Of Contents

Mailing List Stats For This Week

We looked at 3414 posts in 17606K.

There were 868 different contributors. 438 posted more than once. 161 posted last week too.

The top posters of the week were:

1. Linux 2.4.26-rc2 Released

5�Apr�2004�-�15�Apr�2004 (6 posts) Archive Link: "Linux 2.4.26-rc2"

Topics: Disks: IDE, FS: XFS, Power Management: ACPI

People: Marcelo Tosatti,�Paul Mackerras,�Stephen Rothwell

Marcelo Tosatti announced Linux 2.4.26-rc2, saying, "Here goes the second release candidate. It contains an ACPI update, networking updates, IDE updates, XFS update, etc." Paul Mackerras replied:

Any chance of getting this patch in before 2.4.26 final?

This patch is needed for compiling 2.4 with recent versions of gcc, such as the gcc 3.3.3 hammer branch or gcc 3.4. The gcc developers changed the name of the attribute that indicates that something is actually needed, even though gcc can't see why, from "__unused__" to "__used__". This patch copes with that.

The patch is from Stephen Rothwell. He discovered the problem on ppc64, but in fact it would exist on any architecture.

Marcelo accepted the patch.

2. ReiserFS Version 3 Fixes And Updates

6�Apr�2004�-�16�Apr�2004 (22 posts) Archive Link: "[PATCH] reiserfs v3 fixes and features"

Topics: Access Control Lists, FS: ReiserFS, FS: ext2

People: Chris Mason,�Hans Reiser,�Chris Wright,�Marc-Christian Petersen

Chris Mason said:

You can download the set of experimental reiserfs v3 patches from:

Since some of these are in -mm and some are not, there are two series files. series.linus gives you the patches needed for mainline 2.6.5, and gives you the patches needed for 2.6.5-mm1

Most of these are from Jeff Mahoney and I, they include:

bug fixes
logging optimizations
data=ordered support
error messages with device names (based on Oleg's 2.4 patch)
block allocator improvements

Jeff Mahoney's acls and xattrs for reiserfs v3 have been in use in the suse 2.4 kernels and now 2.6 kernels for a while. I've posted for review to namesys many times, but Hans refuses to consider or read the code. I renewed my efforts over the last month to talk with him about the code, but he has ignored it entirely.

His past objections seem to be that he doesn't want new features in v3. The implementation does not change the disk format in any way (xattrs are stored as regular files in a hidden directory) and is stable. I believe reiserfs needs these features in order to stay current in the kernel, so I'm posting for inclusion in -mm. I'm sending Andrew the following patches from


(which is everything except the new block allocator code)

The block allocator improvements is our attempt to reduce fragmentation. The patch defaults to the regular 2.6.5 block allocator, but has options documented at the top of the patch that allow grouping of blocks by packing locality or object id. It also has an option to inherit lightly used packing localities across multiple subdirs, which keeps things closer together in the tree if you have a bunch of subdirs without much in them.

If anyone is interested in experimenting with the block allocator stuff, please let me know.

There were a number of replies. Marc-Christian Petersen said he'd be interested in experimenting with the block allocator stuff, and Chris expanded:

There are a few different sides to the block allocator work.

  1. don't ruin what the current allocator is good at (desktop esp). A sequential tree read of freshly copied data is really fast right now. It could be a little better with some metadata readahead, I'm still trying to safely revive that code.

    The patch tries to keep performance for a full tree read by with the -o packing_groups option. The basic idea is to reuse bitmap groups for new subdirectories until the bitmap group is full. This is done by checking to see how full a given part of the btree is.

  2. Improve the fragmentation under multiple writers. With 20 writers, the default allocator breaks down, fragmenting badly (20% or so). The patch with -o alloc=skip_busy:dirid_groups on makes things sane (3%).

    So, to help test, you need some way of measuring fragmentation and a whole bunch of benchmarks. I like fibmap: (

    But Andrew has a fragmentation tool in the ext2 cvs I think.

Elsewhere, Chris Wright offered a patch, and Chris M. replied, "you'll need some language at the top of the patch giving Hans the copyright on it." But Hans Reiser said that this statement "was very imprecise. describes it better. If you give me the courtesy of allowing me to license reiserfs contributions to third parties (in addition to the usual GPL license), it is appreciated, and it allows me to sometimes earn badly needed funds for reiser4."

3. Page Attribute Table Support In 2.6

12�Apr�2004�-�21�Apr�2004 (20 posts) Archive Link: "PAT support"

Topics: Framebuffer, Ioctls, PCI, Page Attribute Tables

People: Terence Ripperda,�Andi Kleen,�Eric W. Biederman

Terence Ripperda said:

quite a while back, I sent out email about adding Page Attribute Table support to the kernel (

At the time, the concern was being able to mark remapped i/o pages Write Combined in the case that we ran out of MTRRs to do so. This was mainly for the agp aperture and framebuffer. With PCI Express systems coming out, the need changes slightly. PCI Express does not have a centralized aperture like agp that can be marked WC. Instead, individual system pages of memory need to be marked WC via PAT in the page tables. This significantly increases the need for PAT support under linux to maintain high performance levels on PCI Express systems.

I thought the best approach would be to handle some of the original feedback in the code before I came backto ping lkml. I discussed things a little offline with Andi Kleen. He suggested I focus on the simpler i/o regions first, then come back to handling main memory once I had that done and had gotten feedback on it.

I've worked on a mechanism (cachemap) to track what type of caching a region of memory is currently mapped as. when a new region of memory is mapped, cachemap is queried to make sure the new region's caching type matches the old type (or is compatible with the old type). if the cachemap query succeeds, it's safe to map the new i/o region, otherwise it's not safe.

for the first pass, I focused on testing ioremap. so the cachemap queries are only made from ioremap. I also added code to have the mtrr code call the cachemap code (in this case, it's a report rather than a query to indicate the mapping's already made). I've made a few test runs on systems here, and it seems to work fairly well.

this current patch includes the original PAT support and the new cachemap mechanism. note that the cachemap mechanism does not actually change any caching attributes, it only keeps track of the attributes and tests regions. I think the end idea would be that drivers would use the normal ioremap/change_page_attr/remap_page_range mechanisms like they already do, and these mechanisms would in turn use cachemap to make sure there's no conflicts. I'm completely open to how any specific details should work, and any changes needed to be made.

Andi Kleen said Terence's work looked good for a start, and would be worth testing, but still needed some cleanups. He added:

As for an interface - i still think it would be cleaner to just call it from change_page_attr(). Then other users only need to call a single function. But that's easily changed.

To make it really useful I think we need ioremap_wrcomb() and support in the bus/pci mmap function (the PCI layer already has ioctls for this, they are just ignored on i386 right). Then the X server could start using it.

Without any users the testing coverage would be probably not too good, but it needs some testing in the real world before it could be merged first. Maybe it could be simply hooked into the AGP driver and into some DRM driver. Then people would start testing it at least.

Eric W. Biederman replied:

This would also be extremely useful on machines with large amounts of memory, for write-back mappings. With large amounts but odd sized entries it becomes extremely tricky to map all of the memory using mtrrs.

Last I looked the common remedy was to using overlapping mtrrs which the kernel does not understand and that make it impossible for X to setup write-combining MTRRs.

The memory map on x86 shows no hope of getting simpler and mtrrs are getting continually less good at being able to scale so getting PAT support of some kind in the kernel would be extremely good.

Andi agreed, saying:

I already had vendors complaining about this. But for this it will need some more work - the MTRRs need to be fully converted to PAT and then disabled (because MTRRs have higher priority than PAT). Doing so is a lot more risky than what Terrence's patch does currently though. But longer term we will need it.

Also it will still need to handle overlapping ranges. I suppose it will need some simple rules like: converting from UC to WC is always ok.

Andi and Terence went back-and-forth for awhile, with Terence producing updated patches; and the thread petered out.

4. Linux 2.6.5-mm5 Released

12�Apr�2004�-�19�Apr�2004 (23 posts) Archive Link: "2.6.5-mm5"

Topics: Kernel Release Announcement

People: Andrew Morton

Andrew Morton announced 2.6.5-mm5, saying:

5. Obfuscating Data For Security At The DM Level

13�Apr�2004�-�23�Apr�2004 (31 posts) Archive Link: "Using compression before encryption in device-mapper"

Topics: Compression, Device Mapper

People: Timothy Miller,�Guillaume Lac�te,�J�rn Engel

Guillaume Lac�te wanted to use compression at the dm (device mapper) level, because compression would reduce data-redundancy, which would in turn (he supposed) make it more difficult for attackers to interpret the system in order to gain a foothold. Timothy Miller suggested that, "If you're compressing only for the sake of obfuscation, then don't really try to save any space. Use a fast compression algorithm which doesn't necessarily do a great job." But Guillaume replied:

Actually I do _not_ want to do that. The reason for that is that I want to add yet another layer before compression, which would interleave real data with random bytes. These random bytes are not drawn uniformly but rather drawn as to make the distribution on huffman trees (and thus on the encodings) uniform. This ensures that in order to decode my real data, an attacker has to decode the random data first; but since all _compressed_ random sequences are made equi-probable, there is (hopefully) no better way for him to do this than brute force. This is the idea I have (successfully ?) implemented in .

Thus I still want to "compress" my data even if its size grows.

The problem I encounter however is that if forcibly allocating more space than required (e.g. 9 plain blocks every 8 compressed blocks) I will need padding. However padding is generally unwise cryptographically speaking ...

J�rn Engel elsewhere offered his suggestions, adding that he thought a lot of users would be interested in something like this. In Guillaume's original posting, he'd said "I plan to systematically allocate 2 sectors per real sector (space efficiency is _not_ my aim, growing entropy per bit is) and to use a trivial dynamic huffman compression algorithm. Is this solution (which means having half less space than physically available) acceptable ?" J�rn replied now:

Makes sense. One of the zlib developers actually calculated the maximum expansion when zlib-compressing data, so you could even get away with more than 50% net size, but that makes the code more complicated. Your call.

Performance should not be a big issue, as encryption is a performance killer anyway.

Whether it is acceptable depends on the user. Make it optional and let the user decide.

Guillaume replied, "Oops ! I thought it was possible to guarantee with the Huffman encoding (which is more basic than Lempev-Zif) that the compressed data use no more than 1 bit for every byte (i.e. 12,5% more space)." J�rn said this could be true, but he'd like to see the proof. Guillaume replied:

I was referring to the paper by Jeffrey Scott Vitter "Design and Analysis of Dynamic Huffman Codes" (accessible through It defines a refinement of the well-known dynamic Huffman algorithm by Faller, Gallager and Knuth such that the encoded length will use at most _one_ more bit per encoded letter than the optimal two-pass Huffman algorithm (it is also shown that the FGK algorithm an use twice the optimal length + on more bit per letter).

My conclusion comes from the fact that for every text, the optimal two-pass huffman encoding can _not_ be longer than the native encoding (apart from the dictionnary encoding).

Actually I plan to implement the easier FGK algorithm first - if the whole matter makes sense.

J�rn thought this made sense; he wished him luck, and suggested, "You should try to use the crypto/ infrastructure in the kernel, add the compression algorithm there and use it through the normal interface." Other folks continued the technical discussion with Guillaume, which petered out shortly. However, some time later J�rn posted again with some new objections to Guillaume's whole idea. They argued the technical merits briefly, but the discussion dropped off the list before any real conclusion could be formed.

6. Toward Variable, Concurrent Page Sizes

13�Apr�2004�-�15�Apr�2004 (15 posts) Archive Link: "hugetlb demand paging patch part [0/3]"

People: Kenneth W. Chen,�Arjan van de Ven,�David Gibson,�Martin J. Bligh

Kenneth W. Chen said:

In addition to the hugetlb commit handling that we've been working on off the list, Ray Bryant of SGI and I are also working on demand paging for hugetlb page. Here are our final version that has been heavily tested on ia64 and x86. I've broken the patch into 3 pieces so it's easier to read/review, etc.

  1. hugetlb_fix_pte.patch - with demand paging, we can not unconditionally assume valid pmd/pte. Fix it up in arch specific huge_pge_offset() and have all caller check the return value.
  2. hugetlb_demand_generic.patch - this handles bulk of hugetlb demand paging for generic portion of the kernel. I've put hugetlb fault handler in mm/hugetlbpage.c since the fault handler is *exactly* the same for all arch, but that requires opening up huge_pte_alloc() and set_huge_pte() functions in each arch. If people object where it should live. It takes me less than a minute to delete the common code and replicate it in each of the 5 arch that supports hugetlb. Just let me know if that's the case.
  3. hugetlb_demand_arch.patch - this adds additional arch specific fixes for x84 and ia64 when generic demand paging is turned on. Also bulk of the patch is to clean up with functions that no longer needed.

Some caveats: I don't have sh and sparc64 hardware to test. But hugetlb code in these two arch looked like a triplet twin of x86 code. So I'm pretty sure it will work right out of box. I've monkeyed around with ppc64 code and after a while I realized it should be left for the experts. I'm sure there are plenty ppc64 developers out there that can get it done in no time.

Patches relative to linux-2.6.5-mm4 and on top of hugetlb overcommit handling patch posted by Andy Whitcroft.

Arjan van de Ven objected very strongly to the direction Kenneth's and Ray Bryant's work was going. He said, "If you're going to make the kernel deal with different, concurrent page sizes then please do it for real. Or alternatively leave hugetlb to be the kludge/hack it is right now. Anything inbetween is the road to madness..." There were several counters to this. Andy Whitcroft said the work was really 2.7 material anyway, and as such was perfectly valid. Martin J. Bligh said that Kenneth's and Ray's work could be seen as a first (and good) step toward what Arjan's idea of full support. And David Gibson also said, "bear in mind that in a number of ways these patches actually simplify the hugetlb code, although I think most of that is not inherently related to making the hugepage allocation on-demand rather than prefaulted. Nonetheless, doing the demand allocation is actually really easy. Even if you add COW as well, which these patches don't, it doesn't actually make the hack any worse than it was already, but it does make it more useful."

7. Linux 2.6.5-mm6 Released

14�Apr�2004�-�18�Apr�2004 (7 posts) Archive Link: "2.6.5-mm6"

Topics: FS: ext3, Kernel Release Announcement, SMP

People: Andrew Morton

Andrew Morton announced Linux 2.6.5-mm6, saying:

8. SATA Going Into 2.4.27

15�Apr�2004�-�17�Apr�2004 (27 posts) Archive Link: "SATA support merge in 2.4.27"

Topics: Disks: IDE, Serial ATA

People: Marcelo Tosatti,�Stefan Smietanowski,�Andre Hedrick,�Jeff Garzik

Serial ATA, although relatively new, has been moving very quickly. This week, Marcelo Tosatti said:

Jeff Garzik sent me a SATA update to be merged in 2.4.x.

A lot of new boxes are shipping with SATA-only disks, and its pretty bad to not have a "stable" series without such industry-standard support.

This is the last feature to be merged on 2.4.x, and only because its quite necessary.

Any oppositions?

Stefan Smietanowski thought that this was a good idea, given that 2.4 would still be the primary Linux kernel used by folks for quite some time, while 2.6 continued to stablize and become the standard.

Elsewhere, Andre Hedrick accused Marcelo of being bad, on the grounds that he should have included SATA in 2.4.16 long before. Marcelo replied, "SATA 1.0 was posted by Jeff in the past, but I preferred to hold it for a while (to make sure its more stable). It now seems Jeff is more confident with it." There was more acrimonious argument, and the thread petered out. Clearly, Marcelo's 2.4 decisions will continue to be controversial until 2.6 fully takes over.

9. Automatic Bug Checker Reveals Some Kernel Holes

16�Apr�2004�-�20�Apr�2004 (19 posts) Archive Link: "[CHECKER] Probable security holes in 2.6.5"

Topics: Security

People: Ken Ashcraft,�Andrea Arcangeli,�Chris Wright,�Jeff Garzik

Ken Ashcraft posted a long list of potential kernel bugs, explaining:

I'm working at a company called Coverity where we are building an industrial strength derivative of the MC Checker system created at Stanford. I've written a static analysis checker that looks for places where the kernel gets a scalar from the user and then uses it without performing bounds checks. For example, if a driver copies in an integer from the user and then uses that integer as an array index or the length argument to memcpy, the user can cause a buffer overflow.

The error reports below are sorted roughly by their severity. The last 12 of the errors are fairly minor because they are either protected by a capable() check or the scalar is only 8 bits. I also consider it to be a minor error to pass an unchecked value to kmalloc(). I realize that kmalloc() will fail when asked for more than 128k, but it may not be appropriate to allow the user to allocate that much memory. All of these minor errors will be marked by [MINOR] and/or [CAPABLE] tags in the error report.

Chris Wright confirmed a bunch of Ken's bug reports, and posted patches; some of which went directly into the 2.4 and 2.6 kernel trees via Jeff Garzik, and some of which were first modified by folks like Andrea Arcangeli. Chris also disconfirmed several other of Ken's reports, before the thread ended.

10. Linux 2.6.6-rc1-mm1 Released; Some Developer Disconnect

18�Apr�2004�-�21�Apr�2004 (30 posts) Archive Link: "2.6.6-rc1-mm1"

Topics: Kernel Release Announcement, SMP, Version Control, Virtual Memory

People: Andrew Morton,�William Lee Irwin III,�Paul Jackson

Andrew Morton announced Linux 2.6.6-rc1-mm1, saying:

William Lee Irwin III was dismayed to see that some of his recent cpumask fixes had failed to make it into this release. He said, "What do I have to do to get the bare minimal correctness fixes in this area propagated to mainline? The important aspect of these is that they're pertinent to small SMP systems." Andrew replied:

I confess to being moderately exhasperated at the amount of talk and patching going on in the bitmap and cpumask areas. So when your patch floated past with a terse description which was bristling with ifs, buts and maybes I decided to take a pass.

If you want to send it again, cc'ing your co-conspirators and imparting some confidence that this darned thing is actually meandering toward a conclusion, please feel free ;)

William wrote back, CCing Paul Jackson, and saying, "What I believe I have sent is the bare minimum change, with no cleanups or semantic changes. If you could review and/or send approval or the like that would be very helpful for the users of small SMP systems who are affected by the bug(s) you reported." Unfortunately, at around this point it turned out that Paul, whose bug reports had inspired William's work, disagreed that the bugs needed to be fixed, or even that they affected small SMP systems. So that the subthread came to an abrupt halt as the two of them went to private email to sort it out.

11. PS/2 Mouse Fixes; Targus Idiosyncrasy Workarounds

19�Apr�2004�-�20�Apr�2004 (7 posts) Archive Link: "[PATCH] psmouse fixes for 2.6.5"

Topics: Hot-Plugging, Version Control

People: Kim Holviala,�Dmitry Torokhov

Kim Holviala said:

Some fixes for PS/2 mice:

The major change is that the probing of extended protocols is now changed to be more configurable. Previously the driver probed for all the protocols it knew about and stopped when it found one that the mouse accepted. This didn't work with a bunch of mice so now you can choose the protocols which are to be probed.

In current 2.6.5 the parameter "proto=imps" probes all protocols up to ImPS/2. The patch changes this so that "proto=imps" ONLY probes for ImPS/2 and if that fails uses regular PS/2. Similarly "proto=ps2pp,genps,exps" probes for Logitech, Genius and Intellimouse Expolorer and if none found uses the bare PS/2.

Dmitry Torokhov was confused why explicit support for Targus mice was needed, since it seemed to him that the protocol mask could be set correctly by default. But Kim replied, "Targus mice misuse the normal PS/2 protocol so that they can sneak through command-filtering PS/2 ports (like on my Digital HiNote 2000). Basically they output very strange but valid traffic when the wheel is moved. Anyway, this is Linux, and I'd rather force people to turn it on explicitly rather than take the risk of breaking some valid PS/2 device which might theoretically output the same stuff." Dmitry said that even so, folks like distributions would have to turn on that option anyway, in order to be sure to support the maximum number of systems; and so it should be on by default regardless. Kim agreed with this, and Dmitry added, "Btw, I am also trying to work in that area, might be beneficial if we combine our efforts. I just posted bunch of changes on the list, you may also grab them with 'bk pull bk://'" They agreed to talk more privately, and the thread ended.

12. Documentation On Building External Modules

20�Apr�2004�-�21�Apr�2004 (4 posts) Archive Link: "[RFC] kbuild: Documentation - how to build external modules"

Topics: Backward Compatibility, Kernel Build System

People: Sam Ravnborg

On the documentation front, Sam Ravnborg posted a rough and incomplete HOWTO on building external modules:

Building external modules

kbuild offers functionality to build external modules, with the prerequisite that there is a pre-built kernel avialable with full source. A subset of the targets available when building the kernel is available when building an external module.

Building the module

The command looks like his:

make -C <path to kernel src> M=$PWD

For the above command to succeed the kernel must have been built with modules enabled.

To install the modules just being built:

make -C <path to kernel src> M=$PWD modules_install

More complex examples later, the above should get you going in most cases.

Available targets:

make -C $KDIR M=$PWD

Same as if 'modules' was specified. See description of modules target below.

make -C $KDIR M=$PWD modules

Will build the module(s) located in current directory. All output files will be located in the same directory as the module source. No attemps are made to update the kernel source, and it is expected that a successfully make has been executed for the kernel.

make -C $KDIR M=$PWD modules_install

Install the external module(s)

make -C $KDIR M=$PWD clean

Remove all generated files in current directory

Available options:

make -C $KDIR

Used to specify where to find the kernel source. '$KDIR' represent the directory where the kernel source is. Make will actually change directory to the specified directory when executed.

make -C $KDIR M=$PWD

M= is used to tell kbuild that an external module is being built. The option given to M= is the directory where the external module is located. When an external module is being built only a subset of the usual targets are avialable.


Same as M=. The SUBDIRS= syntax is kept for backwards compatibility.

make -C $KDIR M=$PWD help

help will list the available target when building external modules.

A more advanced example

This example shows a setup where a distribution has wisely decided to separate kernel source and output files:

Kernel src:

Output from a kernel compile, including .config:

External module to be compiled:

To compile the module located in the directory above use the following command:

cd /home/user/module/src
make -C /usr/src/linux-<kernel-version> \
O=/lib/modules/linux-<kernel-version>/build \

Then to install the module use the following command:

make -C /usr/src/linux-<kernel-version> \
O=/lib/modules/linux-<kernel-version>/build \
M=$PWD modules_install

The above are rather long commands, and the following chapter lists a few tricks to make it all easier.

Tricks to make it easy

TODO: .... This need to be rewritten......

A make line with several parameters becomes tiresome and errorprone and what follows here is a little trick to make it possible to build a module only using a single 'make' command.

Create a makefile named 'Makefile' with the following content:

---> Makefile:

        $(MAKE) -C /home/sam/src/kernel/v2.6 M=$(PWD) \
                        $(filter-out all,$(MAKECMDGOALS))

obj-m := module.o

---> End of Makefile

When make is invoked it will see the all: rule, and simply call make again with the right parameters.

If a driver is being developed that is targeted for inclusion in the main kernel, an idea is to seperate out the all: rule to a Makefile nemed +makefile (lower capital m) like this:

---> makefile

        $(MAKE) -f Makefile -C /home/sam/src/kernel/v2.6 \
                M=$(PWD) $(MAKECMDGOALS)

---> End of makefile

The kbuild makefile will include only a single statement:

---> Makefile:

obj-m := module.o

---> End of Makefile

When executing make, it looks for a file named makefile, before a file named Makefile. Therefor make will pick up the file named with lower capital 'm'.

Prepare the kernel for building external modules

When building external modules the kernel is expected to be prepared. This includes the precense of certain binaries, the kernel configuration and the symlink to include/asm. To do this a convinient target is made:

make modules_prepare

For a typical distribution this would look like the follwoing:

make modules_prepare O=/lib/modules/linux-<kernel version>/build

TODO: Fill out the following chapters

Module versioning

Local include files

CLFAGS := include ...

Binary only .o files

Use _shipped ...

13. Linux 2.6.6-rc2 Released

20�Apr�2004 (1 post) Archive Link: "Linux 2.6.6-rc2"

Topics: Kernel Release Announcement

People: Linus Torvalds

Linus Torvalds announced 2.6.6-rc2, saying, "Most of the _bulk_ of the rc1->rc2 changes is in the MIPS update, but there's a number of merges here too, notably some networking, firewire, irda and bluetooth updates. Oh, and the regularly scheduled network driver updates too, of course.."

14. Identifying Reverted Patches Based On Changelog 'Cset exclude' Entry

20�Apr�2004 (6 posts) Archive Link: "matching "Cset exclude" changelog entries to the changelog entries they revert."

Topics: Version Control

People: Zack Brown,�Andy Isaacson

I (Zack Brown) was rooting around in the kernel changelogs, and noticed occassionally some entries including text like this:

Cset exclude:|ChangeSet|20020403195622

It was clear that this meant that a previous patch had been reverted; but there was no indication of how to identify that patch in the changelog. I posted to the linux-kernel mailing list, saying:

I count 79 "Cset exclude" changelog entries since 2.5.4-pre1. Is there any way to identify the changelog entry they revert?

for instance, "Cset exclude:|ChangeSet|20020403195622" is in 2.5.8-pre2, as the full text of the changelog entry.

Without a way to identify the particular entry being reverted, I can't rely on the fact that a particular changelog entry represents what actually went into the kernel.

I realize there is almost certainly no way to directly deduce which changelog entry is referenced by a particular 'Cset exclude' entry. But maybe there is some *indirect* way, perhaps a website somewhere that tracks this info?

Andy Isaacson said the following BitKeeper command would give me what I needed:

bk changes -r'|ChangeSet|20020403195622'

For non-BitKeeper users, he also added:

you can construct a working URL by appending the cset key to

like so:|ChangeSet|20020403195622

I tried this, and it worked.

15. High Resolution Timers Update For 2.6

20�Apr�2004�-�23�Apr�2004 (2 posts) Archive Link: "[ANNOUNCE] New high resolution time patch for 2.6.5 kernel"

Topics: POSIX, Real-Time

People: George Anzinger,�Mark Gross

George Anzinger said:

The High Resolution Timers patch for the 2.6.5 kernel has just been posted on sourceforge.

This patch provides an extension to the POSIX clocks and timers to define two new high resolution clocks (CLOCK_REALTIME_HR and CLOCK_MONOTONIC_HR). The resolution of these clocks can be set at CONFIGURE time, with the default being 10 micro seconds. The high res clocks can be used with clock_nanosleep() as well as with the POSIX timers.

This version uses apic timers to obtain much better accuracy and simplicity.

Mark Gross replied happily, "Wow! for my systems this works really well! The jitter is significantly reduced. It would be cool if this could find its way into a major developmet tree."

16. Kernel Mailing List Marked As Spammer By SpamCop

20�Apr�2004�-�22�Apr�2004 (13 posts) Archive Link: " is listed by spamcop"

Topics: Spam

People: Rik van Riel,�Matti Aarnio,�Miles Bader,�Timothy Miller,�Erik Mouw,�Jan De Luyck

Jan De Luyck noticed to his dismay, that, the server hosting the linux-kernel mailing list, had been tagged as a spammer by SpamCop. He asked that something be done to get the server off of their spammers list, so linux-kernel emails could be distributed to users with SpamCop-filtered email. Rik van Riel replied:

Ask your mail server admin. The only people who need to take action are the ones stupid enough to use spamcop's blocklist for outright mail blocking.

The spamcop site even says that their list probably shouldn't be used for outright blocking.

Matti Aarnio also replied to Jan, saying:

Reading SPAMCOP pages I think they are most unwilling to make any exceptions. Per this document:

The only way to handle this is to have smarter people, who are always vigilant enough to look deeply into the message headers and do realize that some spam has leaked thru VGER's lists. They may report those _ONLY_ to VGER's postmaster (several people), who can (to an extent) add keyword based filters to Majordomo.

Any single less savvy person receiving the list could still accidentally get VGER again listed in a number of spam-block lists.

Another would be to run the lists in fully CLOSED mode, which would still let a bunch of viruses thru... (filters are mostly biting on those already, though.) But it would be most nasty mode in other forms...

Miles Bader replied:

I'm confused -- the spamcopy info page you listed implies that hosts are listed if they are an _open relay_, which is a completely different thing from `spam leaking though VGER's lists.'

If VGER actually is an open relay, that's very bad, but presumably something easily solved by the machine's maintainers. Some spam getting through to VGER list recipients, on the other hand, is just annoying (and certainly shouldn't be the cause of any blacklisting).

The spamcop report page seems to say that the listings are due to user reports; could the real problem be clueless users who don't understand the difference above?

Does anyone have a better idea of what's actually going on?

Erik Mouw did some checking, and confirmed that was most definitely not an open relay. Rik added:

While most of the spamcop administrators seem pretty smart, their system definitely is vulnerable to the "Garbage In, Garbage Out" principle.

I'm certain than vger got listed on spamcop due to linux-kernel subscribers reporting to spamcop some of the spam that leaked onto lkml, through Matti's strict filters.

I wouldn't be surprised if some of those same users were now complaining they couldn't get their linux-kernel email. ;)

In my opinion, there are only two types of anti-spam lists that can be responsibly used:

Lists that take the philosophy of "sorry that was our mistake, but we're still not going to make an exception" probably aren't the right lists to use if you care about your email.

The discussion continued briefly, and eventually Timothy Miller said, "It appears that we've been de-listed from SpamCop, probably because I, amongst certainly countless others, complained to them about it. Perhaps they will be smart and permanently whitelist"

Indeed,'s IP number is no longer listed as a spammer at SpamCop.

17. Linux 2.6.6-rc2-mm1 Released

21�Apr�2004�-�24�Apr�2004 (10 posts) Archive Link: "2.6.6-rc2-mm1"

Topics: Framebuffer, Kernel Release Announcement

People: Andrew Morton

Andrew Morton announced Linux 2.6.6-rc2-mm1, saying:

18. ELSA (Enhanced Linux System Accounting) Project Begun

22�Apr�2004 (1 post) Archive Link: "[Announce] Enhanced Linux System Accounting - ELSA project"

Topics: BSD, Version Control

People: Guillaume Thouvenin

Guillaume Thouvenin said:

We are pleased to announce a new project about accounting on Linux. This project is called ELSA (Enhanced Linux System Accounting) and a description follows. Any comments, ideas or participation are welcome.

ELSA (Enhanced Linux System Accounting) announce

The goal of accounting is to collect and report the use of various system resources by applications. Informations, like process time, CPU usage, connect time or disk space usage, provides data that helps the system to adjust the use of resources between processes.

The current BSD-like process accounting that already exists in Linux collects informations on individual users or groups of users. The ELSA project aims to improve and extend the monitoring of resources with different criteria like groups of processes. Another target for this project is to give Linux an homogeneous set of commands for all kinds of accounting (memory, CPU and I/O).

Here is the state of the art about ELSA (Enhanced Linux System Accounting).

19. libata Updates, Including Hotplug Support

24�Apr�2004 (2 posts) Archive Link: "[sata] libata update"

Topics: Hot-Plugging, Serial ATA, Version Control

People: Jeff Garzik

Jeff Garzik said:

I'm slowly and (somewhat) quietly cleaning up the libata internals. This is allow several interesting features to appear in rapid succession: hotplug, random taskfile submission (SMART!), and ATAPI.

This is the first step in cleaning up the internals. Nothing terribly interesting for existing users, except for one key change:

Promise SATA driver has been split. Promise TX2/TX4 SATA remains in "sata_promise". The very-different Promise SX4 support is now found in a new driver "sata_sx4". Promise users, please test and make sure I didn't break anything. It seems to work on my Promise SATA h/w.

Linux 2.6.x patch and changelog:

Linux 2.4.x patch and changelog:

BitKeeper repositories:

J. Ryan Earl was very happy to see this, but there was no discussion.

20. Linux 2.6.6 Released

9�May�2004�-�11�May�2004 (12 posts) Archive Link: "Linux 2.6.6"

Topics: Disks: IDE, FS: CIFS, FS: FAT, FS: NTFS, FS: XFS, Kernel Release Announcement

People: Linus Torvalds,�David Eger

Linus Torvalds announced Linux 2.6.6, saying:

Ok, there it is (well, the tar-file and patches are still being up-loaded, but should be there soon).

NTFS, XFS, FAT and CIFS updates. IDE cache-flush at shutdown fixes. ppc, sparc, s390 and ARM updates (and a few x86-64 fixes).

Holler if I missed anything.

David Eger replied, "The -mm branch has two radeonfb bug fixes; please apply them. One is BenH's. Mine, which fixes a corruption problem with overlapping copyarea()'s is below."

21. Linux 2.6.6-mm1 Released

10�May�2004�-�12�May�2004 (62 posts) Archive Link: "2.6.6-mm1"

Topics: FS: sysfs, Hot-Plugging, Kernel Release Announcement

People: Andrew Morton

Andrew Morton announced 2.6.6-mm1, saying:

22. Status Of InterMezzo In 2.6

12�May�2004 (2 posts) Archive Link: "Re: [PATCH]InterMezzo Patch against linux-2.6.6"

Topics: FS: InterMezzo

People: Linus Torvalds,�Peter J. Braam

Chen Yang asked Linus Torvalds privately why InterMezzo had been removed from the 2.6 kernel; and Linux explained on the list:

It's removed because Peter seems to not want to support it any more, and there didn't seem to be any usage. But if people out there are actually using it, and somebody wants to support it _and_ it is in good working state for 2.6.x, we could certainly bring it back to life.

But if you only do this because you want to fix warnings that people have posted about the sources, and you're not actually seriously using it and maintaining it, then I'll just apply this patch against plain 2.6.6 (so that it doesn't go away if somebody wants to resurrect it later).

In other words - holler if you want to seriously support it. We're not deleting it to be spiteful..

Peter J. Braam replied, "I spoke with Chen and you can just drop InterMezzo now. It is easy to maintain as a module outside the kernel, we did that for some years."

Sharon And Joy

Kernel Traffic is grateful to be developed on a computer donated by Professor Greg Benson and Professor Allan Cruse in the Department of Computer Science at the University of San Francisco. This is the same department that invented FlashMob Computing. Kernel Traffic is hosted by the generous folks at All pages on this site are copyright their original authors, and distributed under the terms of the GNU General Public License version 2.0.