Re: git: c499ad6f997c - main - virtio: Use bus_dma for ring and indirect buffer allocations

From: Herbert J. Skuhra <herbert_at_gojira.at>
Date: Mon, 09 Mar 2026 18:25:32 UTC
On Mon, 09 Mar 2026 17:38:24 +0100, Andrew Turner wrote:
> 
> 
> > On 8 Mar 2026, at 17:39, Herbert J. Skuhra <herbert@gojira.at> wrote:
> > 
> > On Tue, 03 Mar 2026 18:37:57 +0100, Andrew Turner wrote:
> >> 
> >> The branch main has been updated by andrew:
> >> 
> >> URL: https://cgit.FreeBSD.org/src/commit/?id=c499ad6f997c8c5f61c88925e6d1e826d0c0f6c4
> >> 
> >> commit c499ad6f997c8c5f61c88925e6d1e826d0c0f6c4
> >> Author:     Sarah Walker <sarah.walker2@arm.com>
> >> AuthorDate: 2026-03-03 16:08:11 +0000
> >> Commit:     Andrew Turner <andrew@FreeBSD.org>
> >> CommitDate: 2026-03-03 16:29:15 +0000
> >> 
> >>    virtio: Use bus_dma for ring and indirect buffer allocations
> >> 
> >>    While the majority of virtio platforms will be fully coherent, some may
> >>    require cache maintenance or other specific device memory handling (eg for
> >>    secure partitioning). Using bus_dma allows for these usecases.
> >> 
> >>    The virtio buffers are marked as coherent; this should ensure that sync
> >>    calls are no-ops in the common cases.
> >> 
> >>    Reviewed by:    andrew
> >>    Sponsored by:   Arm Ltd
> >>    Differential Revision:  https://reviews.freebsd.org/D54959
> >> ---
> >> sys/dev/virtio/virtio_ring.h |  27 ++++--
> >> sys/dev/virtio/virtqueue.c   | 216 +++++++++++++++++++++++++++++++++++++------
> >> 2 files changed, 209 insertions(+), 34 deletions(-)
> > 
> > After this change I see a lot of "kernel: vtnet0: watchdog timeout on
> > queue xx" errors on amd64 (arm64 seems to be OK).
> > 
> > Reverting this commit resolves the issue.
> 
> Can you try the change in https://reviews.freebsd.org/D55766? It re-adds memory barriers for amd64.

Yes, the patch seems to resolve the issue. Thanks.