Date: Thu, 13 Nov 1997 16:00:54 -0500 (EST) From: Alfred Perlstein <perlsta@cs.sunyit.edu> To: hackers@FreeBSD.org Subject: Re: BSDI F0 bug workaround implementation (help with understanding) Message-ID: <Pine.BSF.3.96.971113155923.15617C-100000@server.local.sunyit.edu> In-Reply-To: <199711131907.MAA28899@usr08.primenet.com>
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I've been following the thread on the Pentium CPU bug, i was wondering how a workaround is possible? it just seems very interesting. -Alfred On Thu, 13 Nov 1997, Terry Lambert wrote: > > I'm not sure I understand the full implications of the impact of this > > hack, although it is worrisome. Judging by what my pentium book says about > > the layout of the IDT, it seems like it will increase interrupt latency > > for page faults and many maskable interrupts. Can anyone more > > knowledgeable than I comment on this? Page fault overhead on freebsd is > > pretty high: would a short-cut make sense that does not go through the > > full vm system for this? Otherwise page fault overhead may come close to > > doubling ... > > Only the first 7 IDT entries are affected (at least in the Linux > workaround), not the whole table. > > On the minus side, the impact *is* non-zero. > > Like the FPU bug, since a workaround exists, it's likely to be swept > under the software as well. 8-(. > > > Terry Lambert > terry@lambert.org > --- > Any opinions in this posting are my own and not those of my present > or previous employers. >
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