Date: Tue, 27 Mar 2001 23:00:04 -0800 (PST) From: natedac@kscable.com To: freebsd-ports@FreeBSD.org Subject: Re: ports/25958: Xfree86's savage and vesa drivers%2 Message-ID: <200103280700.f2S704G45252@freefall.freebsd.org>
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The following reply was made to PR ports/25958; it has been noted by GNATS.
From: natedac@kscable.com
To: freebsd-gnats-submit@FreeBSD.org, natedac@kscable.com
Cc: natedac@kscable.com, jhb@FreeBSD.org
Subject: Re: ports/25958: Xfree86's savage and vesa drivers%2
Date: Wed, 28 Mar 2001 00:51:49 -0600 (CST)
Thanks to lots of help from BigSpoon on #BSDcode/EFnet (jhb@FreeBSD.org),
here's a more proper way to fix the MTRR problem that plages some machines
like mine. This will allow the MTRR support to be disabled at will either
in /boot/loader.conf or at the boot prompt. It appears that today the
copy of this file sitting on ftp.freebsd.org has been changed slightly (so
a patch/diff against my week-old copy would be of little use anyways ;-)
Anyways, here we go:
Edit /usr/src/sys/i386/i386/i686_mem.c
Somewhere near the start of the file, add these two lines:
------------------------------------------------------------------------------
static int mtrrs_disabled;
TUNABLE_INT_DECL("machdep.mtrrs_disabled", 0, mtrrs_disabled);
------------------------------------------------------------------------------
Then, go to the end of the file, and make these changes to
i686_mem_drvinit()...
------------------------------------------------------------------------------
static void
i686_mem_drvinit(void *unused)
{
/* First, check if the user wants to allow MTRR at all */
if (mtrrs_disabled) { return; }
/* Ok, MTRR is allowed, so try for i686 MTRRs */
if ((cpu_feature & CPUID_MTRR) &&
((cpu_id & 0xf00) == 0x600) &&
((strcmp(cpu_vendor, "GenuineIntel") == 0) ||
(strcmp(cpu_vendor, "AuthenticAMD") == 0))) {
mem_range_softc.mr_op = &i686_mrops;
}
}
-----------------------------------------------------------------------------
Finally, add a line to /boot/loader.conf to disable the MTRR support if
you need to (leaving it out or mis-spelling the variable name will cause
MTRR support to be detected and enabled normally):
machdep.mtrrs_disabled = 1
I guess at this point, the original PR should remain open until the bug is
solved in a more formal manner, but this seems to be an effective
workaround. So far, I haven't seen any ill effects from disabling MTRR's.
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