On Thu, 2022-08-18 at 23:11 +0300, Martin-Éric Racine wrote: > On Thu, Aug 18, 2022 at 10:59 PM Ben Hutchings <b...@decadent.org.uk> wrote: > > > > Control: retitle -1 [i386] Unconditional LFENCE instructions in > > FILL_RETURN_BUFFER > > Control: tag -1 confirmed upstream > > Control: found -1 5.18.14-1 > > > > On Wed, 2022-08-17 at 11:42 +0200, Etienne Vogt wrote: > > > I can confirm that this bug also occurs on Athlon XP systems (Generic VIA > > > KT333 motherboard, CPU AMD Athlon(tm) XP 2600+) : kernel panic early on > > > boot. > > > > > > I suspect someone thought it would be a good idea to compile the kernel > > > for P4 only, as both PIII and Athlon XP processors lack the SSE2 > > > instruction set. > > > > > > > That was a good guess, though we don't change the configuration like > > that in stable updates. > > > > The RETbleed mitigations, which are not needed on these CPUs or even > > functional on 32-bit kernels, interact with the Spectre v2 mitigations, > > which *are* used on these CPUs. And unfortunately the RETbleed > > mitigations added some unconditional LFENCE instructions, which should > > be conditional since they are part of SSE2. > > > > As a temporary workaround, disabling the Spectre v2 mitigation with the > > kernel parameter "nospectre_v2" should allow this kernel version to run > > on older CPUs without SSE2. We'll fix this properly in a later update. > > That breakage affects Stable. > > Expecting people to go and use workarounds on what was meant to be a > stable update isn't acceptable.
Martin, you know we're all volunteers here, so don't take that tone. I was trying to be helpful in offering an alternative to holding back the upgrade. > I really hope that the fix will be pushed within the next 24 hours > with high urgency. This is unlikely to happen. Ben. -- Ben Hutchings I haven't lost my mind; it's backed up on tape somewhere.
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