Possible critical VIA vt82c686a chip bug (private question)
A message that is not in the archive (sent off-list or not yet received): [email protected]
Quoted 38 lines · Vojtech Pavlik
Quoted 31 lines · Yoann Vandoorselaere
Quoted 10 lines · Yoann Vandoorselaere
Quoted 8 lines
...
Have you any idea what is the relation between time and this chip ?
Also, I'm experiencing the problem for several month on my workstation and I never could find where it was comming from... how did you do ?
Quoted 8 lines
Well, it integrates both the i8253 PIT and the vt82c586 IDE controller.
I first located the wrong time was coming from
gettimeofday()and not from the other sources of time the kernel provides. And then I was tracking the problem (which actually is an underflow - the chip bug causes some time offset variables go negative -0xffffffffmicroseconds is about 1:20 hours). And this way I got to the spot where the patch cures the problem.Ok, here is what I experienced :
First what is strange is that :
- I'm using SCSI
- I just have an IDE disk for mp3.
The IDE subsystem is never used heavilly...I've experienced the problem after some time of
heavy scsi IO, my screen under X was going black (like with dpms) When I was moving the mouse, the image was coming back for < 1 seconds, then black screen...Quoted 4 lines
The only fix was to kill X then to reboot.
Anyway, thanks for your explaination...
I'll do a feedback for this patch ASAP.
Quoted 7 lines
Interesting. If it's caused by SCSI as well (might be), then it's not caused by heavy IDE activity but rather than that it could be heavy BusMastering activity instead (The IDE chip does BM as well).
I'm still wondering if it could be a Linux kernel bug (bad/concurrent accesses to the i8253 registers), this has to be checked.
How sure are you that the chip is actually buggy? I ran into something similar a while ago, when I mixed the two arguments to an outb in a driver, and ended up writing MYPORT into the timer instead of 0x40 into MYPORT.
Bart
Signature · 7 lines
Bart Hartgers - TUE Eindhoven Get my GPG key at http://etpmod.phys.tue.nl/bart/pubkey.gpg - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] Please read the FAQ at http://www.tux.org/lkml/
Quoted 11 lines · On Fri, Oct 27, 2000 at 02:04:58PM +0200, [email protected] wrote:
Quoted 7 lines
Interesting. If it's caused by SCSI as well (might be), then it's not caused by heavy IDE activity but rather than that it could be heavy BusMastering activity instead (The IDE chip does BM as well).
I'm still wondering if it could be a Linux kernel bug (bad/concurrent accesses to the i8253 registers), this has to be checked.
How sure are you that the chip is actually buggy? I ran into something similar a while ago, when I mixed the two arguments to an outb in a driver, and ended up writing MYPORT into the timer instead of
0x40into MYPORT.
I'm *not* sure. It just looks like a reasonable explanation. It doesn't happen on Intel chips and older VIA chips, it only happens on new VIA chips, and the code is the same all the time. Also, it happens both with 2.2 and 2.4 kernels ...
Signature · 6 lines
Vojtech Pavlik SuSE Labs - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] Please read the FAQ at http://www.tux.org/lkml/
Quoted 10 lines · Vojtech Pavlik
I'm *not* sure. It just looks like a reasonable explanation. It doesn't happen on Intel chips and older VIA chips, it only happens on new VIA chips, and the code is the same all the time. Also, it happens both with 2.2 and 2.4 kernels ...
--
Vojtech Pavlik
SuSE Labs
Do you have a method guaranteed to reproduce this? I have a newer VIA chipset and haven't (yet) observed this problem.
Host bridge: VIA Technologies, Inc. VT8371 [KX133] (rev 2).
PCI bridge: VIA Technologies, Inc. VT8371 [KX133 AGP] (rev 0).
ISA bridge: VIA Technologies, Inc. VT82C686 [Apollo Super South](rev 34).
IDE interface: VIA Technologies, Inc. Bus Master IDE (rev 16).
Bridge: VIA Technologies, Inc. VT82C686 [Apollo Super ACPI] (rev
48).
Multimedia audio controller: VIA Technologies, Inc. AC97 Audio
Controller (rev 32).
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-- TimO
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