Re: [PATCH 8/8] virtio_ring.h: do not include <stdint.h> from exported header

[Arnd Bergmann]

On Tue, Apr 5, 2022 at 7:35 AM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote:
>
> On Mon, Apr 04, 2022 at 10:04:02AM +0200, Arnd Bergmann wrote:
> > The header is shared between kernel and other projects using virtio, such as
> > qemu and any boot loaders booting from virtio devices. It's not technically a
> > /kernel/ ABI, but it is an ABI and for practical reasons the kernel version is
> > maintained as the master copy if I understand it correctly.
>
> Besides that fact that as you correctly states these are not a UAPI at
> all, qemu and bootloades are not specific to Linux and can't require a
> specific kernel version.  So the same thing we do for file system
> formats or network protocols applies here:  just copy the damn header.
> And as stated above any reasonably portable userspace needs to have a
> copy anyway.

I think the users all have their own copies, at least the ones I could
find on codesearch.debian.org. However, there are 27 virtio_*.h
files in include/uapi/linux that probably should stay together for
the purpose of defining the virtio protocol, and some others might
be uapi relevant.

I see that at least include/uapi/linux/vhost.h has ioctl() definitions
in it, and includes the virtio_ring.h header indirectly.

Adding the virtio maintainers to Cc to see if they can provide
more background on this.

> If it is just as a "master copy" it can live in drivers/virtio/, just
> like we do for other formats.

It has to be in include/linux/ at least because it's used by a number
of drivers outside of drivers/virtio/.

        Arnd