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SubjectRe: Possible critical VIA vt82c686a chip bug (private question)
On Thu, Oct 26, 2000 at 12:04:21PM -0400, Richard B. Johnson wrote:

> ../drivers/block/ide.c, line 162, on version 2.2.17 does bad things
> to the timer. It writes 0 to the control-word for timer 0. This
> does the following:
> o Selects timer 0.
> o Latches the timer.
> o Selects mode 0.
> o Programs it to a 16 bit counter.
> The result is a latched (stopped) counter. Bits 5 and 4 should have been
> selected. Then you read bits 0-7 from 0x40, followed by bits 8-15 from
> the same port.
> Also, there is no spin-lock protecting access to these ports. If anybody
> else is mucking with the timer, all bets are off.

Well, at least on 2.4.0-test9, the above timing code is #ifed to
DISK_RECOVERY_TIME > 0, which in turn is #defined to 0 in

So this is not our problem here. Anyway I guess it's time to hunt for
i8259 accesses in the kernel that lack the necessary spinlock, even when
they're not probably the cause of the problem we see here.

Vojtech Pavlik
SuSE Labs
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