[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: Problems with APIC on versions 4.9 and later (4.8 works)
Em qua., 20 de jan. de 2021 às 12:13, Jürgen Groß <jgross@xxxxxxxx> escreveu: > > On 20.01.21 09:50, Jan Beulich wrote: > > On 19.01.2021 20:36, Claudemir Todo Bom wrote: > >> I visually compared all the messages, and the only thing I noticed was that > >> 4.14 used tsc as clocksource and 4.8 used xen. I tried to boot the kernel > >> with "clocksource=xen" and the problem is happening with that also. > > > > There's some confusion here I suppose: The clock source you talk > > about is the kernel's, not Xen's. I didn't think this would > > change for the same kernel version with different Xen underneath, > > but the Linux maintainers of the Xen code there may know better. > > Cc-ing them. > > This might depend on CPUID bits given to dom0 by Xen, e.g. regarding > TSC stability. Based on this observation I've installed the cpuid utility on the system and obtained the output of it on all scenarios: raw kernel, xen 4.8.5 and xen 4.14.0. I used "dom0_max_vcpus=1 dom0_vpus_pin smt=false" on both xen command lines since this is the only way I can get to a command prompt with xen 4.14. the outputs of the cpuid command are attached. I've compared with diff -u (files also attached): * the differences of both xen with the raw kernel output * the differences between both xen It is clear that xen 4.14 is changing a lot how the dom0 sees the cpu, disabling a lot of features present both on raw kernel and 4.8 outputs. I don't know if this alone can indicate where the problem is being triggered. Next I will try to build xen from source with a "binary tree" approach between 4.8 and 4.9 commits, but as I will use development source, I think that is very probable I get with a lot of other problems. Best regards, Claudemir Attachment:
cpuid-xen-4.8.txt Attachment:
cpuid-xen-4.14.txt Attachment:
cpuid-diff-xen-4.8-4.14.diff Attachment:
cpuid-diff-rawkernel-xen-4.8.diff Attachment:
cpuid-rawkernel.txt Attachment:
cpuid-diff-rawkernel-xen-4.14.diff
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