[vfio-users] intel_iommu=on and aacraid / Adaptec 3805

[David]

the command "dmesg | grep -i dma"  Give no results.  Is there anything
else i should check Alex?

If the solution to this is to submit a bug report, who should i send
it too?  I believe the AACRAID driver is built into the Linux kernel.

On Tue, Jul 12, 2016 at 9:51 AM, Alex Williamson
<alex.williamson at redhat.com> wrote:
> On Sun, 10 Jul 2016 13:17:41 -0500
> David <david283 at gmail.com> wrote:
>
>> I have run into a strange problem, while setting up my Fedora 24 box for
>> KVM, i noticed that my raid array stopped showing as an available drive.
>> After a lot of troubleshooting and reinstalling linux to this PC 2 more
>> times, i have narrowed it down to one setting in my GRUB config.
>>  intel_iommu=on
>>
>> Just taking that one setting out and rebuilding my grub2-efi.cfg will make
>> the array readable again.  When IOMMU is on, the system can see that there
>> is a raid card and array, but it lists the partition table as unknown.  It
>> also will not successfully create a new GPT partition table on the array.
>> With IOMMU off, it can read the partition table and partition fine, read
>> and write data, and everything works fine.
>>
>> My raid is 4 1TB disks in Raid 10e, GPT partition formatted NTFS.
>>
>> $ lspci -v -s 03:0e.0
>> 03:0e.0 RAID bus controller: Adaptec AAC-RAID
>>     Subsystem: Adaptec 3805
>>     Flags: bus master, stepping, 66MHz, medium devsel, latency 32, IRQ 57
>>     Memory at fa600000 (64-bit, non-prefetchable) [size=2M]
>>     Expansion ROM at fa800000 [disabled] [size=256K]
>>     Capabilities: <access denied>
>>     Kernel driver in use: aacraid
>>     Kernel modules: aacraid
>
>
> No DMAR faults in dmesg?  There's a fair chance this is one of those
> devices that does DMA with the wrong requester ID and therefore
> enabling the IOMMU prevents it from working.  We have a mechanism in
> the kernel to handle such DMA aliasing if you can verify the issue.
> Thanks,
>
> Alex



-- 
David
david283 at gmail.com