Date: Thu, 24 Apr 1997 20:24:52 +0900 From: KATO Takenori <kato@eclogite.eps.nagoya-u.ac.jp> To: rb@gid.co.uk Cc: kato@eclogite.eps.nagoya-u.ac.jp, freebsd-current@freebsd.org Subject: Re: Cyrix DX2/4 Message-ID: <199704241124.UAA03726@gneiss.eps.nagoya-u.ac.jp> In-Reply-To: Your message of "Thu, 24 Apr 1997 11:06:33 %2B0100" References: <l03020905af84e000c937@[194.32.164.2]>
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From: Bob Bishop <rb@gid.co.uk> Subject: Re: Cyrix DX2/4 Date: Thu, 24 Apr 1997 11:06:33 +0100 > I didn't have any problem until the new CPU flags were introduced. In old revision of initcpu.c, init_486() modified CR0 to disable CPU cache as: load_cr0(rcr0() | CR0_CD | CR0_NW); CD bit in CR0 becomes 1 after this line, and never become 0 when CYRIX_CACHE_WORKS is not set. This measn CPU cache is always disabled. This is the reason of performance loss you got. I changed init_486() and current init_486() doesn't diable CPU cache (I deleted above line). > (a) the BIOS is providing any necessary initialisation or (b) they don't > need any. If you doesn't set CYRIX_CACHE_WORKS, init_486() do nothing on DX2/DX4 box in initcpu.c revision >= 1.3. Does initcpu.c revision 1.3 still causes performance loss? If so, please let me know. ---- KATO Takenori <kato@eclogite.eps.nagoya-u.ac.jp> Dept. Earth Planet. Sci., Nagoya Univ., Nagoya, 464-01, Japan PGP public key: finger kato@eclogite.eps.nagoya-u.ac.jp ------------------- Powered by FreeBSD(98) -------------------
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