Messages in this thread | | | From | Arnd Bergmann <> | Date | Thu, 8 Feb 2018 22:50:15 +0100 | Subject | Re: [BUG] x86 : i486 reporting to be vulnerable to Meltdown/Spectre_V1/Spectre_V2 |
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On Thu, Feb 8, 2018 at 6:27 PM, tedheadster <tedheadster@gmail.com> 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. > > 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).
VIA machines are available for pocket change in many countries, this one is what I'd get if I wanted to test over here:
http://www.ebay.de/itm/IGEL-UD2-D200-VIA-C7-M-500MHz-1GB-1GB-Flash-Memory-Thin-Client-ohne-Netzteil/301860030372
Similarly, the 6x86 (Cyrix, ST or IBM branded are identical) is really easy to get by itself and should fit in many Socket 7 mainboards, which you apparently already have.
Arnd
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