From: Cornelia Huck <cohuck@redhat.com>
To: David Hildenbrand <david@redhat.com>
Cc: virtio-comment@lists.oasis-open.org,
teawater <teawaterz@linux.alibaba.com>,
Marek Kedzierski <mkedzier@redhat.com>,
"Michael S . Tsirkin" <mst@redhat.com>
Subject: [virtio-comment] Re: [PATCH v1] virtio-mem: minor clarification regarding read-access to unplugged blocks
Date: Fri, 20 Nov 2020 16:13:30 +0100 [thread overview]
Message-ID: <20201120161330.740d694e.cohuck@redhat.com> (raw)
In-Reply-To: <20201116191629.47661-1-david@redhat.com>
On Mon, 16 Nov 2020 20:16:29 +0100
David Hildenbrand <david@redhat.com> wrote:
> Let's clarify that we don't expect all DMA to work with unplugged blocks.
> We really only give guarantees when reading from unplugged memory blocks
> via the CPU, e.g., as done by Linux when creating a system dump via
> kdump: the new kernel will copy the content of the old (crashed) kernel
> via the CPU to user space, from where it will find its final destination
> inside the dump file. Note that dumping via makedumpfile under Linux will
> avoid reading unplugged blocks completely.
>
> This is a preparation for device passthrough to VMs, whereby such
> dedicated devices might not be able to read from unplugged memory blocks.
>
> Let's document that this scenario is possible, and why this handling is
> in place at all.
>
> Cc: teawater <teawaterz@linux.alibaba.com>
> Cc: Marek Kedzierski <mkedzier@redhat.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Cornelia Huck <cohuck@redhat.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
> virtio-mem.tex | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
Looks reasonable to me.
Acked-by: Cornelia Huck <cohuck@redhat.com>
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next prev parent reply other threads:[~2020-11-20 15:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-16 19:16 [virtio-comment] [PATCH v1] virtio-mem: minor clarification regarding read-access to unplugged blocks David Hildenbrand
2020-11-20 15:13 ` Cornelia Huck [this message]
2020-11-27 10:39 ` [virtio-comment] " David Hildenbrand
2020-11-27 11:02 ` Cornelia Huck
2020-12-02 9:25 ` David Hildenbrand
2020-12-02 10:15 ` Cornelia Huck
2020-12-02 10:30 ` [virtio-comment] " David Hildenbrand
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