From: "Michael S. Tsirkin" <mst@redhat.com>
To: Marcel Holtmann <marcel@holtmann.org>
Cc: virtio-dev@lists.oasis-open.org
Subject: Re: [virtio-dev] Correct way to specify virtio_foo_config structures?
Date: Sat, 24 Dec 2022 13:26:05 -0500 [thread overview]
Message-ID: <20221224131902-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <809854E1-BB69-4639-8B53-C33E88C78E85@holtmann.org>
On Tue, Dec 20, 2022 at 03:51:13PM +0100, Marcel Holtmann wrote:
> Hi,
>
> what is the correct way for a VIRTIO_F_VERSION_1 modern device to specify the
> virtio_foo_config structure. Should I make it __attribute__((packed))? What field
> types should be used. Everything __virtio{16,32} or better __le{16,32}? Can we
> have __u8 and do they have to 16-bit or 32-bit aligned.
>
> When looking at the various examples, I see multiple combinations. What is the
> prefered virtio_cread accessor method to be used. For example the virtio_cread_le
> states something like “modern” in his comment. So the preference is to specify
> the virtio_foo_config in little-endian?
>
> Any insights are appreciated.
>
> Regards
>
> Marcel
__leXX and __u8 and things have to be size aligned (so no alignment
requirements for u8 arrays). Add explicit padding as necessary.
__attribute__((packed)) should be generally avoided.
For config access virtio_cread_le/virtio_cwrite_le are preferred.
>
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prev parent reply other threads:[~2022-12-24 18:26 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-20 14:51 [virtio-dev] Correct way to specify virtio_foo_config structures? Marcel Holtmann
2022-12-24 18:26 ` Michael S. Tsirkin [this message]
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