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. 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, -- Andreas Trottmann -- To UNSUBSCRIBE, email to debian-kernel-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
