Re: sata_sil24: swiotlb buffer is full ?

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Mon, Oct 31, 2016 at 10:18:25AM -0600, Tejun Heo wrote:
> Hello,
> 
> On Sat, Oct 29, 2016 at 11:40:29PM -0400, Andrew Ryder wrote:
> > I have some disks attached to a "Silicon Image, Inc. SiI 3124 PCI-X Serial
> > ATA Controller" and it repeatedly locks up the system with the message
> > whenever there is heavy disk i/o. The system the controller is attached to
> > is a via EPIA-M910 board.
> > 
> > sata_sil24: 0000:06:03.0: swiotlb buffer is full: 65536 bytes)
> > DMA: Out of SW-IOMMU space for 65536 bytes at device .."
> > sata_sil24 0000:06:03.0: swiotlb buffer is full (sz: 65536 bytes .."
> > 
> > For the past week I have been running with two additional boot parameters
> > (iommu=allowdac swiotlb=131072) which seem to have solved the issue, but I
> > was curious if this is a driver bug or not?

Usually it means that the device (sta_sil24) can only handle certain
DMA addresses and hence needs the assistance of the bounce buffers (swiotlb).

Increasing the number of them is the right way to make it work.

I would call this hardware limitation - if you provide the lspci -n -s 06:03.0
one can look in the driver and see where it sets the DMA mask.

> 
> (cc'ing swiotbl maintainer, hi!)
> 
> That looks like iotlb area running out.  I don't think there's much to
> be done from driver side and we've traditionally been pretty bad at
> handling iotlb errors.  Konrad, do you have any ideas?
> 
> Thanks.
> 
> -- 
> tejun