Re: Data-corruption bug in VIA chipsets

From: Dan Podeanu (pdan@spiral.extreme.ro)
Date: Fri Apr 13 2001 - 23:38:00 EST


On 13 Apr 2001, Doug McNaught wrote:

> Alan Cox <alan@lxorguk.ukuu.org.uk> writes:
>
> > > Here might be one of the resons for the trouble with VIA chipsets:
> > >
> > > http://www.theregister.co.uk/content/3/18267.html
> > >
> > > Some DMA error corrupting data, sounds like a really nasty bug. The
> > > information is minimal on that page.
> >
> > What annoys me is that we've known about the problem for _ages_. If you look
> > the 2.4 kernel has experimental workarounds for this problem. VIA never once
> > even returned an email to say 'we are looking into this'. Instead people sat
> > there flashing multiple BIOS images and seeing what made the difference.
>
> Is this problem likely to affect 2.2.X? I have a VIA-based board on
> order (Tyan Trinity) and I don't plan to run 2.4 on it anytime soon
> (it's upgrading a stock RH6.2 box).
>

We've had HUGE problems with 2.4.x kernels and VIA based boards. We have
here 3 VIA boards with Athlon/850 and Duron/900 CPUs. The problem goes
like this:

Compile 2.4.3 with VIA and Athlon support.
Reboot.
Ooopses (between 1 and continuously scrolling of them) occur at random
periods of time, between mounting the root filesystem and 2-3 minutes of
functionality.

Note that the problem occurs with all versions of 2.4 but not with
2.2.17-2.2.19. Also, enabling or disabling DMA doesn't help fix the
problem.

After several compiles, it appears that compiling with 586 cpu support
instead of Athlon resulted in a working, stable kernel (which is rather
strange imo, given there are different CPUs but the same board model).
However, compiling with 386 support didn't (which was my first guess of a
stable system).

I was a bit lazy and didn't save/ksymoops any of the oopses, but will do
if this is not a well-known problem (and it appears that more or less it
is).

My lspci:
00:00.0 Host bridge: VIA Technologies, Inc.: Unknown device 0305 (rev 03)
00:01.0 PCI bridge: VIA Technologies, Inc.: Unknown device 8305
00:07.0 ISA bridge: VIA Technologies, Inc. VT82C686 [Apollo Super] (rev
40)
00:07.1 IDE interface: VIA Technologies, Inc. VT82C586 IDE [Apollo] (rev
06)
00:07.2 USB Controller: VIA Technologies, Inc. VT82C586B USB (rev 16)
00:07.4 Bridge: VIA Technologies, Inc. VT82C686 [Apollo Super ACPI] (rev
40)
00:07.5 Multimedia audio controller: VIA Technologies, Inc. VT82C686
[Apollo Super AC97/Audio] (rev 50)
00:0b.0 Ethernet controller: Intel Corporation 82557 [Ethernet Pro 100]
(rev 08)01:00.0 VGA compatible controller: Matrox Graphics, Inc. MGA G400
AGP (rev 04)

(although the cards stuck in the PCIs aren't the same for all three
systems)

and /proc/cpuinfo (from the kernel with 586 support):
processor : 0
vendor_id : AuthenticAMD
cpu family : 6
model : 4
model name : AMD Athlon(tm) Processor
stepping : 2
cpu MHz : 851.961
cache size : 256 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov
pat pse36 mmx fxsr syscall mmxext 3dnowext 3dnow
bogomips : 1697.38

I know that all in all this is rather irrelevant, but if further
information is needed, drop me a line and I'll try be a good boy (tm) :)

Yours, Dan.

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