Date: Sat, 24 Mar 2001 12:28:20 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: Dave Tweten <tweten@nas.nasa.gov> Cc: freebsd-stable@FreeBSD.ORG Subject: Re: 4.3-RC Kernel Buffer Corruption (Was: 4.3-BETA makeworld of current STABLE Fails) Message-ID: <200103242028.f2OKSKR05745@earth.backplane.com> References: <200103240249.f2O2ng602441@gilmore.nas.nasa.gov>
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I've gone through a diff of the -stable kernel between Feb 15
and March 6. It took a while. I had to hack cvs to allow date
specs to include branch names (else cvs diff -D -D works off of
HEAD). I'll send an email with that patch a little later after
I clean it up.
I went through around 26786 lines of diffs. All sorts stuff was
changed/added, such as the kqueue stuff, M_ZERO, networking, some
softupdates cleanups, a minor VM fix, etc.... but most of it
just doesn't apply to a buildworld.
Two things stand out.
* The allocation of memory was changed to allocate from
the end of memory backwards rather then the beginning of memory
forwards.
* ATA/IDE was adjusted to support new DMA modes for VIA chipsets.
I think there are two possibilities here:
(1) You have bad memory somewhere and the memory ordering change
is simply making it apparent.
(2) Your motherboard is using the VIA chipset and the new kernels
are using a different DMA mode then the Feb16 kernel, and
there is a DMA related bug.
It should be easy to check both. To check #2 look at the 'dmesg'
output when booting the working kernel and when booting the new
kernel. Boot in bootverbose mode (I think that's -v from the bootstrap
prompt).
To check #1 try replacing the memory in the box.
I will look at the changes made to the memory ordering in vm/vm_page.c
and to zalloc later tonight, but I don't think they introduced any
bugs.
-Matt
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