Re: [PATCH] Initialize PIIX3 IDE channels as "enabled"

Dor Laor
2007-03-13T10:07:11Z

>>Gregory Haskins wrote:
>>> This patch initializes the PIIX3 IDE controllers IDE channels as
>>enabled. They were previously unconfigured by QEMU.
>>>
>>> IDE devices have been broken on our local lab systems since the
>>introduction of QEMU 0.9.0 (KVM-14). Tracing the Linux driver for
PIIX3
>>initialization revealed that the "enabled" bits (bit 7 in the
PCI-CONFIG
>>space at address 0x41 and 0x43, port 0 and 1 respectively) were not
set.
>>In a bare-metal system, it would typically be the role of the BIOS to
>>enable something like this, so this solution may be a hack. I
speculate
>>that the real bug may be something introduced into Bochs about the
same
>>time as the 0.9.0 deployment, but I have not investigated this.
>>Nonetheless, unless there is a specific run-time switch to
enable/disable
>>the IDE channels, initializing them in QEMU vs Bochs is probably 6 of
one,
>>half dozen of the other.
>>>
>>>
>>
>>Is the bug present in stock qemu-0.9.0?
>>
>>I'm no acpi expert, but this may be related to our acpi breakage.
>
>I thought so too and guess what?
>We can install Windows with acpi! (The installation is running now,
didn't
>complete yet but it passed the stage it had stucked before!

Opsss,
I was too fast on the trigger; it didn't solve anything regarding acpi.
No long ago we had a problem on the trunk with windows installation.
It failed if the flag -no-acpi was not used.
When I checked your patch the problem disappeared but when windows
installation completed I discovered that it didn't use the acpi HAL.
So I checked without the patch and got the same result too.
Probably recent commits fixed the crash and from now the -no-acpi flag
is not required during installation.
Well it was a long shot.

>
>Good job.
>
>>
>>--
>>Do not meddle in the internals of kernels, for they are subtle and
quick
>to
>>panic.
>>
>>
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