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Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and c
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access |
Date: |
Thu, 8 Aug 2013 17:30:35 +0100 |
On 8 August 2013 17:25, Anthony Liguori <address@hidden> wrote:
> Peter Maydell <address@hidden> writes:
>> On 8 August 2013 17:07, Anthony Liguori <address@hidden> wrote:
>>> CPU data structures are still read as big endian though.
>>
>> Do you have an example of what you mean by "CPU data structure"?
>
> MMU tlb hash table. If you grep ldl target-ppc/* you'll see that there
> are only a few cases where bswap occurs.
Oh, right, that sort of in-memory data structure. If I
understand correctly, the equivalent of that for ARM would
be the MMU translation tables; on ARM there's a system
control register bit for which endianness those are.
>> Any stl_phys() should [in an ideal design] be tied to a
>> "bus master" which has its own idea of which endianness
>> it is. That is, an stl_phys() for a DMA controller model
>> ought to use the endianness programmed for the DMA controller,
>> not whatever the CPU happens to be using.
>
> We have the DMA API that attempts to do this but maybe we need to
> generalize it a bit more...
>
> I think it's pretty true that we need a context and that the context
> for, say instruction fetch, is distinct from the context for load/store
> instructions.
A context might also give us a place to put other interesting
information which in hardware gets passed around as transaction
attributes on the bus, such as "is this a userspace or privileged
instruction".
-- PMM
- [Qemu-devel] [PATCH 6/7] hw/scsi/virtio-scsi: use virtio wrappers to access headers., (continued)
- [Qemu-devel] [PATCH 6/7] hw/scsi/virtio-scsi: use virtio wrappers to access headers., Rusty Russell, 2013/08/08
- [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Rusty Russell, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Anthony Liguori, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Andreas Färber, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Anthony Liguori, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Daniel P. Berrange, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Anthony Liguori, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Peter Maydell, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Anthony Liguori, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access,
Peter Maydell <=
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Rusty Russell, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Anton Blanchard, 2013/08/09
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Peter Maydell, 2013/08/09
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Anthony Liguori, 2013/08/09
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Peter Maydell, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Anthony Liguori, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Andreas Färber, 2013/08/08
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Rusty Russell, 2013/08/09
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Peter Maydell, 2013/08/09
- Re: [Qemu-devel] [PATCH 1/7] virtio: allow byte swapping for vring and config access, Rusty Russell, 2013/08/12