Date: Sat, 19 Apr 1997 12:26:26 +0100 From: Bob Bishop <rb@gid.co.uk> To: KATO Takenori <kato@eclogite.eps.nagoya-u.ac.jp> Cc: freebsd-bugs@freefall.freebsd.org Subject: Re: kern/3292: Cyrix 486 performance problem Message-ID: <l03020908af7e5add7359@[194.32.164.2]> In-Reply-To: <199704190324.MAA08105@gneiss.eps.nagoya-u.ac.jp> References: Your message of "Fri, 18 Apr 1997 21:36:54 %2B0100" <l03020904af7d8b1d935f@[194.32.164.2]>
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At 4:24 +0100 19/4/97, KATO Takenori wrote: >I read initcpu.c and compared it to old locore.s, then I found a >solution of Cyrix 486 CPU cache. That is just do: > > Delete cache disable code in init_486dlc(). > >1. BIOS on old motherboards may not initialize registers of Cyrix > 486. Thus, CPU cache is not enabled at reset time. >2. BIOS on newer motherboards initialize registers of Cyrix 486. Thus, > CPU cache is enabled by BIOS. > >In case 1, usere should recompile with CYRIX_CACHE_WORKS to enable CPU >cache, because neither BIOS nor FreeBSD kernel enable it. In case 2, >BIOS enables CPU cache and FreeBSD kernel doesn't disable it, even >though CYRIX_CACHE_WORKS is not set. I think that would do it. I suspect that with these DX2 parts the cache is on by default rather than being turned on by the BIOS (as it would have to be for SLC/DLC), but it amounts to the same thing. -- Bob Bishop (0118) 977 4017 international code +44 118 rb@gid.co.uk fax (0118) 989 4254 between 0800 and 1800 UK
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