Author: tychon
Date: Fri Apr 19 13:43:33 2019
New Revision: 346386
URL: https://svnweb.freebsd.org/changeset/base/346386
Log:
remove the 4GB boundary requirement on PCI DMA segments
Reviewed by: kib
Discussed with: jhb
Sponsored by: Dell EMC Isilon
Differential Revision:
As Ryan suggests r232260 should be recommitted to get acc(4) fixed.
However, given the age of the devices involved and the lack of support by the
standard, I’d say the threshold isn’t met to reinstate the boundary globally
preemptively.
To get the insurance, which may not even be necessary, yo
Yeah, it might be turning into an old wives tale at this point. I clearly
remember
it being discussed at the PCI-SIG in late 2003 when PCIe 1.0 was in its final
draft stages. However, that was a long time ago, and it’s possible that even
if it’s a limitation in some version or another of the spe
+scottl@, who I believe explained this to us in the first place.
As I recall, it had something to do with 64-bit DMA being expressed as
segment base + 32-bit offset. DMA engines that blindly try to cross a
32-bit boundary end up back at the start of the segment and read/write
the wrong memory loc
I had looked for the aac change, but wasn't able to find it, perhaps because I
looked at tags created in aac.c rather than aac_pci.c. I agree aac will need to
be re-patched. I'm not really certain how many other devices are actually
broken.
They would all be due to a firmware bug, nothing inhere
Following up, this is what will have to be re-instated in the aac driver:
http://svn.freebsd.org/changeset/base/232260
However, my biggest concern is that we have no idea how many new
devices with the broken behaviour might have been introduced since we
fixed the problem in general. How does Lin
This change makes me *very* uncomfortable. It was originally brought
in due to issues with Adaptec RAID cards using the aac(9) driver. The
symptoms of the bug included silent corruption of data as it was
written to disk. Are we sure that this change is a good idea, given
how catastrophic it is w
Author: tychon
Date: Fri Apr 19 13:43:33 2019
New Revision: 346386
URL: https://svnweb.freebsd.org/changeset/base/346386
Log:
remove the 4GB boundary requirement on PCI DMA segments
Reviewed by: kib
Discussed with: jhb
Sponsored by: Dell EMC Isilon
Differential Revision:
