Re: [Qemu-devel] [PATCH 1/8] virtio_get_byteswap: function for endian-ambivalent targets using virtio.

["Andreas Färber" <afaerber@suse.de>]

Am 18.02.2014 15:48, schrieb Alexander Graf:
> On 02/18/2014 01:38 PM, Greg Kurz wrote:
>> From: Rusty Russell <rusty@rustcorp.com.au>
>>
>> virtio data structures are defined as "target endian", which assumes
>> that's a fixed value.  In fact, that actually means it's
>> platform-specific.
>>
>> The OASIS virtio 1.0 spec will fix this.  Meanwhile, create a hook for
>> little endian ppc (and potentially ARM).  This is called at device
>> reset time (which is done before any driver is loaded) since it
>> may involve a system call to get the status when running under kvm.
>>
>> [ fixed checkpatch.pl error with the virtio_byteswap initialisation,
>>    ldq_phys() API change, Greg Kurz <gkurz@linux.vnet.ibm.com> ]
>> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
>> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
>> ---
>>   hw/virtio/virtio.c                |    6 ++
>>   include/hw/virtio/virtio-access.h |  132
>> +++++++++++++++++++++++++++++++++++++
>>   include/hw/virtio/virtio.h        |    2 +
>>   stubs/Makefile.objs               |    1
>>   stubs/virtio_get_byteswap.c       |    6 ++
>>   5 files changed, 147 insertions(+)
>>   create mode 100644 include/hw/virtio/virtio-access.h
>>   create mode 100644 stubs/virtio_get_byteswap.c
>>
>> 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;
> 
> Could this be a virtio object property rather than a global? Imagine an
> AMP guest system with a BE and an LE system running in parallel
> accessing two separate virtio devices. With a single global that would
> break.

Déjà vu... ;)

http://lists.nongnu.org/archive/html/qemu-devel/2013-08/msg01043.html

Andreas

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