[systemd-devel] Illegal CPUID instruction causes systemd core dump

[Mike Gilbert]

On Thu, Dec 28, 2017 at 3:18 PM, Lennart Poettering
<lennart at poettering.net> wrote:
> On Do, 28.12.17 14:07, tedheadster (tedheadster at gmail.com) wrote:
>
>> I am doing regression testing on old hardware. systemd-233 just
>> generated the following error on startup:
>>
>> traps:systemd[1] trap invalid opcode ip:b7d97361 sp:bfa2f6bc error:0
>> in libsystemd-shared-233.so[b7d3e000+1cc000]
>> systemd[1]: Caught <ILL>, dumped core as pid 78.
>> systemd[1]: Freezing execution
>>
>> I believe it is getting an illegal instruction trap on this first
>> generation 486 because it is calling "cpuid" in detect_vm_cpuid()
>> without first checking if the hardware supports it; it doesn't in this
>> case.
>>
>> The gcc compiler provides a workaround in the cpuid.h header file. You
>> can call __get_cpuid_max() first and check the return value > 0.
>>
>> https://stackoverflow.com/questions/14266772/how-do-i-call-cpuid-in-linux#14266932
>>
>> The Linux kernel still supports the 486 so we have to code around this
>> case, even if it is ancient hardware.
>
> Please send a patch for this. We lack the relevant hardware and
> can't test this. In fact, for most such portability support for
> less-than-mainsrtream systems we rely on external patches.

I created a PR for this. I have not tested it on a VM, or on an i486.
Hopefully one of the CI systems can cover the former case. ;-)

https://github.com/systemd/systemd/pull/7758