Messages in this thread |  | | From | "Petr Vandrovec" <> | Date | Wed, 19 Sep 2001 20:57:59 MET-1 | Subject | Re: Re[2]: [PATCH] Athlon bug stomper. Pls apply. |
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On 19 Sep 01 at 11:43, Dan Hollis wrote: > On Wed, 19 Sep 2001, Linus Torvalds wrote: > > It is _probably_ an undocumented performance thing, and clearing that > > bit may slow something down. But it might also change some behaviour, > > and knowing _what_ the behaviour is might be very useful for figuring > > out what it is that triggers the problem. > > AFAIK noone has even tested it yet to see what it does to performance! Eg > it might slow down memory access so that athlon-optimized memcopy is now > slower than non-athlon-optimized memcopy. And if it turns out to be the > case, we might as well just use the non-athlon-optimized memcopy instead > of twiddling undocumented northbridge bits...
No, we cannot. On boxes which do not work with athlon optimized kernels any user can execute athlon's fast_page_copy from userspace, causing corruption on completely unrelated pages, eventually leading to kernel crash... So you cannot allow untrusted users on such machine. Best regards, Petr Vandrovec vandrove@vc.cvut.cz
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