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Re: [Xen-devel] [xen-unstable] Commit 2ca9fbd739b8a72b16dd790d0fff7b75f5488fb8 AMD IOMMU: allocate IRTE entries instead of using a static mapping, makes dom0 boot process stall several times.

Monday, August 26, 2013, 4:15:10 PM, you wrote:

>>>> On 26.08.13 at 14:34, Sander Eikelenboom <linux@xxxxxxxxxxxxxx> wrote:

>> Monday, August 26, 2013, 1:23:01 PM, you wrote:
>>>>>> On 26.08.13 at 13:07, Sander Eikelenboom <linux@xxxxxxxxxxxxxx> wrote:
>>>> Don't know that for sure, will check if there are any related messages in 
>>>> dmesg
>>>> I only see it enabling HPET, but i don't see anything about MSI ..
>>> The primary indicator, if I'm not mistaken, would be 3 IRQs in
>>> /proc/interrupts that show type HPET_MSI (and I suspect you
>>> don't see any).
>> Ah found out why, another quirk and silently applying:
>> /*
>>  * HPET MSI on some boards (ATI SB700/SB800) has side effect on
>>  * floppy DMA. Disable HPET MSI on such platforms.
>>  * See erratum #27 (Misinterpreted MSI Requests May Result in
>>  * Corrupted LPC DMA Data) in AMD Publication #46837,
>>  * "SB700 Family Product Errata", Rev. 1.0, March 2010.
>>  */
>> static void force_disable_hpet_msi(struct pci_dev *unused)
>> {
>>         hpet_msi_disable = 1;
>> }
>> how many quirks can a machine have ...

> Indeed.

> In any case - I take this as a sign that I'll submit the earlier
> patch as is, without your Tested-by (because you couldn't
> really test other than that your box doesn't stall anymore).

Well my problem of the ACPI table not being correct is perhaps not the major 
issue but the
erratum above probably is .. if wikipedia is not mistaken .. this one seems to 
be in 3 series of southbridges:

HPET operation with MSI causes LPC DMA corruption on devices using LPC DMA 
(floppy, parallel port, serial port in FIR mode) because MSI requests are 
misinterpreted as DMA cycles by the broken LPC controller[5]

With the 900 series having a nice extra problem with sata and multi msi vectors 
.. hope linux already has a quirk for that .. with regard to recent changes.


Floppy and parallel are probably not the most used devices anymore, serial 
perhaps, so don't know if it shouldn't be disabled altogether on these 
But i assume someone from AMD would be best to comment on that ...

> Thanks for your patience,
> Jan

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