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From: brian@shift.lan.awfulhak.org (Brian Somers)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: Am5x86/P75 WB caching...
Date: 21 Mar 1997 14:46:10 GMT
Organization: Awfulhak Ltd.
Lines: 40
Message-ID: <5gu6vi$bm9@ui-gate.utell.co.uk>
References: <5gnrql$2ut@usenet88.supernews.com>
<5gpmhp$hc7@verdi.nethelp.no> <5gso69$eqb@usenet88.supernews.com>
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In article <5gso69$eqb@usenet88.supernews.com>,
jca@bighorn.accessnv.com (J.C. Archambeau) writes:
> Steinar Haug (sthaug@nethelp.no) wrote:
>
>:| I just upgraded the CPU in my EISA/VLB motherboard from an i486DX/33 to
>:| an AMD Am5x86/P75 (133). FreeBSD (2.2-BETA) properly indentifies the CPU,
>:| but it states that the L1 cache is in write through mode at bootup. Does
>:| FreeBSD disable write back caching of the Am5x86? If it does, what
>:| define or kernel configuration parameter do I need to change?
>
>: FreeBSD works fine with writeback. Here's the boot info from a 5x86-133
>: running in an ASUS PVI-486SP3 motherboard:
>
>: FreeBSD 2.2-BETA_A #1: Sun Jan 12 15:25:39 MET 1997
>: sthaug@bizet.nethelp.no:/local/usr/src/sys/compile/GATE
>: Calibrating clock(s) relative to mc146818A clock ... i8254 clock: 1193220 Hz
>: CPU: AMD Am5x86 Write-Back (486-class CPU)
>: Origin = "AuthenticAMD" Id = 0x4f4
>: real memory = 25165824 (24576K bytes)
>: avail memory = 22835200 (22300K bytes)
>
>: At least on this motherboard you need to enable writeback with a jumper.
>
> Is there a way to force FreeBSD to enable write back caching though? It
> may not be enabling it for my particular chipset (SiS EISA chipset). I
> know that write back is working from MS-DOS and Win 3.x because of
> the results of various utilities (i.e. cachchk6).
> --
> /* | Spam violation - e-mail dumped...
> ** Internet: jca@accessnv.com | Don't blame me, I didn't vote for Clinton.
> ** jca@anv.net | Intel is the word for 'errata.'
> */
There's talk about adding some CPU options to the kernel in -current
at the moment. You may want to subscribe to freebsd-hackers@freebsd.org.
--
Brian <brian@awfulhak.demon.co.uk> <brian@freebsd.org>
<http://www.awfulhak.demon.co.uk>
Don't _EVER_ lose your sense of humour !