On Mon, May 18, 2009 at 05:11:41PM +0200, Andreas U. Trottmann wrote: > Package: linux-image-2.6.26-2-686-bigmem > Version: 2.6.26-15 > > Hello, > > The Linux kernel sources upon which > linux-image-2.6.26-2-686-bigmem is based are suffering from a > bug, which only affects the (relatively rare) "summit" SMP > architecture. It is found in IBM xSeries servers such as the > x440 or x445. > > On these servers, linux-image-2.6.26-2-686-bigmem only correctly > identifies and uses one CPU, regardless of the number of CPUs > actually installed. > > The bug is documented and resolved on linux-kernel: > > http://lkml.indiana.edu/hypermail/linux/kernel/0807.3/0493.html > > The patch responsible for the resolution is the following: > > --- a/include/asm-x86/mach-summit/mach_apic.h 2008-07-24 18:06:39.000000000 > -0700 > +++ b/include/asm-x86/mach-summit/mach_apic.h 2008-07-24 18:09:29.000000000 > -0700 > @@ -122,7 +122,7 @@ static inline physid_mask_t ioapic_phys_ > > static inline physid_mask_t apicid_to_cpu_present(int apicid) > { > - return physid_mask_of_physid(0); > + return physid_mask_of_physid(apicid); > } > > > I report the bug against a lenny kernel, as I don't have any such system > running > testing or unstable. The current linux kernel source in unstable, > linux-2.6_2.6.29-5, > appears to have the file structure reorganized. The relevant file appears to > be > arch/x86/include/asm/summit/apic.h, and the bug appears still to be present: > apicid_to_cpu_present still returns physid_mask_of_physid(0) instead of > (apicid). > > However, currently I cannot test whether the fix is still relevant. > > If it is of help, I could try to boot an unpatched linux-2.6_2.6.29-5 kernel > on a > summit machine and compare the number of identified CPUs with a patched > linux-2.6_2.6.29-5 > kernel.
A fix has been committed. It would be helpful if you could test a lenny snaphot build and confirm the fix. Information on installing snapshots is available here: http://wiki.debian.org/DebianKernel The version you will want to test will be >= 2.6.26-16~snapshot.13633 and should be available after the next daily build cycle. > In any case, it could probably be a good idea to include the fix in the next > lenny > kernel update, as it does render those multi-CPU machines relatively useless, > and > the fix does not affect anyone else. > > > > With kind regards, > -- dann frazier -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org