Re: [Regression] 3.15 mmc related ext4 corruption with qemu-system-arm

[Ulf Hansson]

On 12 June 2014 14:15, Peter Maydell <peter.maydell@xxxxxxxxxx> wrote:
> On 12 June 2014 13:09, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>> A simple fix; for the arm_variant, go back to use the old behaviour.
>>
>> A quite simple fix; Invent a new primecell-periphid and a new
>> corresponding variant and use the old behaviour for this variant. The
>> new primecell-periphid then needs to be provided through DT for the
>> QEMU dtb.
>>
>> Is there any of the above solution you see as the preferred one?
>
> Those both sound like workarounds, not fixes, to me. Somebody
> needs to identify whether the bug here is in:
>  * the kernel (unlikely, but possibly the kernel has a race
>    condition that only gets triggered by QEMU's "operations
>    that take time in h/w happen instantaneously in emulation"
>    behaviour)
>  * the QEMU model of the PL181
>  * the QEMU model of the SD card
> and then fix whichever of these is not conforming to the
> specs/docs/etc.

You are right. But...

Since we (or actually me) have made the ARM model to break (it worked
nicely before), I just wanted to restore the behaviour as a quick fix.
I believe going into this in detail can take some more time,
especially if it's related to the ARM model, right!?

Kind regards
Uffe

>
> Also, there's no such thing as a "QEMU dtb", at least for
> most of our board models. QEMU models the actual hardware
> (sometimes buggily or incompletely) and so should use the
> exact same dtb you would use with the hardware.
>
> thanks
> -- PMM
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