Date: Tue, 18 Nov 1997 19:30:17 +0900 From: KATO Takenori <kato@migmatite.eps.nagoya-u.ac.jp> To: Pierre.Beyssac@hsc.fr Cc: freebsd-security@freebsd.org Subject: Re: now a Cyrix processor bug Message-ID: <199711181030.TAA06758@gneiss.eps.nagoya-u.ac.jp> In-Reply-To: Your message of "Tue, 18 Nov 1997 10:54:17 %2B0100" References: <19971118105417.FC32400@mars.hsc.fr>
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> Has anynone seen this? > > There seems to be a bug on the Cyrix, similar but not identical > to the Pentium's. However the workaround on the Cyrix is apparently > much simpler (you only need to disable LOCK mode in the CCR, if I > understood the fix right). 3.0-current and RELENG_2_2 (including 2.2.5) have following option: CPU_CYRIX_NO_LOCK which enables weak locking. Because I didn't know of the Coma bug, and recomended setting of NO_LOCK bit is 0 in the BIOS writer's guide, NO_LOCK bit is not modified when above option is not set. Because SMP of FreeBSD doesn't support non-Intel chipsets, CPU_CYRIX_NO_LOCK options may have no harmful effect. Also, another fix via special registers is propsed. But, Cyrix doesn't disclose the meanings of such registers. When Cyrix discloses the meaning of registers, I will implement latter fix. ---- KATO Takenori <kato@ganko.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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