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

Alex Williamson alex.williamson at redhat.com
Wed Jul 13 16:03:19 UTC 2016


On Tue, 12 Jul 2016 20:29:13 -0500
David <david283 at gmail.com> wrote:

> 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.

How about sending the full, uncut, unfiltered dmesg out first?  Have
you tried adding iommu=pt as a boot option?  Thanks,

Alex

> 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  
> 
> 
> 




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