Bug#973414: libmozjs-78-0: invalid opcodes in libmozjs when launching GDM3

[Martin-Éric Racine]

pe 30. lokak. 2020 klo 13.50 Simon McVittie (smcv at debian.org) kirjoitti:
> On Fri, 30 Oct 2020 at 10:35:21 +0200, Martin-Éric Racine wrote:
> > [  165.903916] traps: gnome-shell[869] trap invalid opcode ip:b5518f8a sp:b17d6d80 error:0 in libmozjs-78.so.78.3.0[b4b98000+98c000]
>
> Which specific x86 CPU is this? I see `uname -m` is i586 rather than the
> expected i686 (and there's only one core), so presumably it's somewhere
> close to our architecture baseline, either above or below.  The baseline
> is -march=i686 since gcc-6_6.1.1-1 and stretch, according to the research
> I did for <https://wiki.debian.org/ArchitectureSpecificsMemo>.

Geode LX800. This is technically a 686 but it doesn't support PAE, so
the CPU family remains 586.

> The /proc/cpuinfo would be useful information, since that includes a list
> of capability flags.

processor    : 0
vendor_id    : AuthenticAMD
cpu family    : 5
model        : 10
model name    : Geode(TM) Integrated Processor by AMD PCS
stepping    : 2
cpu MHz        : 498.025
cache size    : 128 KB
physical id    : 0
siblings    : 1
core id        : 0
cpu cores    : 1
apicid        : 0
initial apicid    : 0
fdiv_bug    : no
f00f_bug    : no
coma_bug    : no
fpu        : yes
fpu_exception    : yes
cpuid level    : 1
wp        : yes
flags        : fpu de pse tsc msr cx8 sep pge cmov clflush mmx mmxext
3dnowext 3dnow cpuid 3dnowprefetch vmmcall
bugs        : sysret_ss_attrs spectre_v1 spectre_v2 spec_store_bypass
bogomips    : 996.05
clflush size    : 32
cache_alignment    : 32
address sizes    : 32 bits physical, 32 bits virtual
power management:

> cc gcc maintainers (in the absence of an i386 porter contact): Is there
> a more formal/detailed specification for what CPU extensions we do and
> don't intend to require on i386?

AFAIK plain 686 (without PAE) is the baseline. Debian's
linux-image-686 actually is configured for Geode.

> Does Firefox work on this machine?
>
> Did older versions of GNOME Shell (buster or stretch) work on this machine?
> If yes, do they have acceptable performance in practice?

Both have worked until whatever is currently in Stable. Firefox as-is,
gnome-shell using the X wrapper.

Martin-Éric