On Wed, 1 Apr 2015 20:42:13 +0200
"Michael S. Tsirkin" <> wrote:
> pci spec says what width access to use for 32, 16 and 8
> bit fields, but does not explicitly say what to do for
> 32 bit fields. As we have text that says driver must
s/32/64/
> treat 64 bit accesses as non-atomic, this seems
> to imply driver should always do two 32 bit wide accesses.
>
> Let's make this an explicit requirement, and require
> devices to support this.
>
> VIRTIO-139
>
> Signed-off-by: Michael S. Tsirkin <>
> ---
> conformance.tex | 1 +
> content.tex
| 19 ++++++++++++++
-----
> 2 files changed, 15 insertions(+), 5 deletions(-)
(...)
> +For device configuration access, the driver MUST use 8-bit wide
> +accesses for 8-bit wide fields, 16-bit wide and aligned accesses
> +for 16-bit wide fields and 32-bit wide and aligned accesses for
> +32-bit and 64-bit wide fields. For 64-bit fields, the driver MAY
> +access each of the high and low 32-bit parts of the field
> +independently.
Doesn't the last sentence follow from "use 32-bit wide accesses"
already?
