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Re: Problems with APIC on versions 4.9 and later (4.8 works)
Hi,
I do not have serial output on this setup, so I recorded a
video with boot_delay=50 in order to be able to get all the
kernel messages: https://youtu.be/y95h6vqoF7Y
This is running 4.14 from debian bullseye (testing).
I'm also attaching the dmesg output when booting xen 4.8
with the same kernel version and same parameters.
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.
The "start" of the problem is that when the kernel gets to
the "Freeing unused kernel image (initmem) memory: 2380K" it
hangs and stays there for a while. After a few minutes it
shows that a process (swapper) is blocked for sometime (image
attached)
About finding what happened on the 4.8 -> 4.9 window, I
may be able to build some code from git to check, I will try
to find the build instructions to look at this.
Best regards,
Claudemir
On
18.01.2021 21:15, Claudemir Todo Bom wrote:
> Sorry for the simultaneous post on xen-users and
xen-devel, but as I noted
> that the problem appears only for versions of xen that
are >= 4.9, I think
> that developers may have a look at this.
Dropping xen-users.
> I recently bought a generic mainboard and a Xeon
E5-2926v2 CPU, it is a 12
> core, 24 threads cpu.
>
> My system was already running on another machine with xen
4.11 on a debian
> 10 system and after replacing the mainboard it didn't
boot.
>
> After many tries I noticed that downgrading to the
previous version of Xen
> (4.8, available on Debian 9) works well. I also tried a
lot of variations
> for the dom0 kernel, all of them with the same results.
>
> All my tests were done with 4.11, but I checked with a
live version of
> Alpine Linux (3.7.3, with Xen 4.9.4) that the system
doesn't boot on that
> release also.
>
> With more research I noticed that if I limit dom0 to use
only one CPU
> (dom0_max_vcpus=1) the system boots up, I didn't check if
guest VM worked,
> but I suppose that they would not be able to use the
other 23 vcpus
> available, anyway, a system with one vcpu for dom0 would
be very slow I
> think.
>
> I've noticed also that if I keep dom0 to use more than
one core but disable
> acpi on the dom0 kernel, it boots up, unfortunately this
is not
> sufficient because I cannot use any device attached to
the system (not even
> the usb keyboard). This only helps to detect that the
problem may be in the
> ACPI/APIC code.
>
> I tried many variations with parameters related with ACPI
and APIC. None of
> them was satisfactory, always ended on a halted system or
a self rebooting
> one.
>
> Can anyone point me to a solution for this?
For this we first of all need details about your problem: A
full
boot log ideally, or if this isn't available anything at least
allowing us to see what exactly goes wrong (and with this I
mean
the first thing going wrong, not later possible follow-on
issues
from earlier problems), like screen shots. And this again
ideally
with master / staging Xen, or if that's not feasible with as
new
a version as possible.
I don't suppose you'd be up for bisecting the 4.8 ... 4.9
window
to determine when exactly your issue was introduced?
Jan
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xen-4.8.log
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IMG_20210119_154753.jpg
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