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Re: [Qemu-devel] [PATCH v5 1/8] virtio_get_byteswap: function for endian
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v5 1/8] virtio_get_byteswap: function for endian-ambivalent targets using virtio |
Date: |
Tue, 25 Feb 2014 16:21:21 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Feb 21, 2014 at 12:28:11PM +0100, Greg Kurz wrote:
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index aeabf3a..4fd6ac2 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -19,6 +19,9 @@
> #include "hw/virtio/virtio.h"
> #include "qemu/atomic.h"
> #include "hw/virtio/virtio-bus.h"
> +#include "hw/virtio/virtio-access.h"
> +
> +bool virtio_byteswap;
>
> /*
> * The alignment to use between consumer and producer parts of vring.
> @@ -546,6 +549,9 @@ void virtio_reset(void *opaque)
>
> virtio_set_status(vdev, 0);
>
> + /* We assume all devices are the same endian. */
> + virtio_byteswap = virtio_get_byteswap();
> +
> if (k->reset) {
> k->reset(vdev);
> }
In the previous version it was pointed out that the global is nasty.
A cleaner solution is a per-VirtIODevice enum device_endian value which
gets passed to lduw_phys_internal()/stl_phys_internal()/etc.
Now the same code can be used for:
1. Host == guest-endian
2. Host != guest-endian
3. "Everything is little-endian" (VIRTIO 1.0)
Keeping it per-device means we can have both legacy and VIRTIO 1.0
devices in a guest.
That's better than hacking in a global now and having to undo it when
VIRTIO 1.0 support gets merged.
Stefan
- [Qemu-devel] [PATCH v5 0/8] virtio endian-ambivalent target fixes, Greg Kurz, 2014/02/21
- [Qemu-devel] [PATCH v5 1/8] virtio_get_byteswap: function for endian-ambivalent targets using virtio, Greg Kurz, 2014/02/21
- Re: [Qemu-devel] [PATCH v5 1/8] virtio_get_byteswap: function for endian-ambivalent targets using virtio,
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH v5 2/8] virtio: allow byte swapping for vring and config access, Greg Kurz, 2014/02/21
- [Qemu-devel] [PATCH v5 3/8] virtio-net: use virtio wrappers to access headers, Greg Kurz, 2014/02/21
- [Qemu-devel] [PATCH v5 4/8] virtio-balloon: use virtio wrappers to access page frame numbers, Greg Kurz, 2014/02/21
- [Qemu-devel] [PATCH v5 5/8] virtio-blk: use virtio wrappers to access headers, Greg Kurz, 2014/02/21
- [Qemu-devel] [PATCH v5 6/8] virtio-scsi: use virtio wrappers to access headers, Greg Kurz, 2014/02/21
- [Qemu-devel] [PATCH v5 7/8] virtio-serial-bus: use virtio wrappers to access headers, Greg Kurz, 2014/02/21
- [Qemu-devel] [PATCH v5 8/8] virtio-9p: use virtio wrappers to access headers, Greg Kurz, 2014/02/21
- Re: [Qemu-devel] [PATCH v5 0/8] virtio endian-ambivalent target fixes, Stefan Hajnoczi, 2014/02/25