Messages in this thread | | | From | Ondrej Zary <> | Subject | Re: [BUG] x86 : i486 reporting to be vulnerable to Meltdown/Spectre_V1/Spectre_V2 | Date | Fri, 9 Feb 2018 09:41:41 +0100 |
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On Thursday 08 February 2018, tedheadster wrote: > On Thu, Feb 8, 2018 at 12:02 PM, David Laight <David.Laight@aculab.com> wrote: > > From: Arnd Bergmann > > > >> Sent: 08 February 2018 15:23 > > > > ... > > > >> The Winchip is what eventually turned into the VIA Nano, which does > >> have speculative execution, but I don't think the earlier C3 and C7 did, > >> they are much closer to the original Winchip design. > > > > We had terrible trouble getting (IIRC) the C7 to execute functions > > that were called in 16bit mode and returned in 32bit mode and v.v. > > (for boot code bios calls). > > The problems seemed to imply that it was caching return addresses > > and the translation (to uops) of the instructions that followed. > > So it would effectively decode the first few bytes in the wrong mode. > > So there might be scope for one of these attacks. > > > > OTOH these devices were so slow that I doubt any are used for anything > > serious - and certainly won't get a kernel update even if they are. > > > > Also worth nothing that the difference between the cpu and memory > > speeds is much lower - so far fewer instructions could be speculatively > > executed while waiting a cache miss. > > > > Tempting to disable everything. > > > > David > > You might think this absolutely crazy, but I would be willing to test > such systems if I can get my hands on the needed hardware that I lack. > I am already doing sanity testing on Intel > i486/i586/i586-MMX/i686-PentiumPro systems, I just don't have the > clone cpus (Cyrix, etc). > > While few people are using the 32bit kernel, I don't think we want to > kill it completely just yet. > > - Matthew
I have a working Cyrix MII (was actively using it last year, now upgraded to a P3-based Celeron). Some AMD CPUs too - K6(maybe -2 or -3?), not sure about K5 and also a Rise mP6. But never got a WinChip.
So the question is: what to test?
BTW. Kernel was not able to identify mP6 CPU 6 years ago, patches were ignored.
-- Ondrej Zary
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