Re: [PATCH for-7.0 v2 1/2] ivshmem.c: change endianness to LITTLE_ENDIAN

[Daniel Henrique Barboza <danielhb413@gmail.com>]

On 11/24/21 09:55, Markus Armbruster wrote:
> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
> 
>> On 11/24/21 10:29, Daniel Henrique Barboza wrote:
>>> The ivshmem device, as with most PCI devices, uses little endian byte
>>> order. However, the endianness of its mmio_ops is marked as
>>> DEVICE_NATIVE_ENDIAN. This presents not only the usual problems with big
>>> endian hosts but also with PowerPC little endian hosts as well, since
>>> the Power architecture in QEMU uses big endian hardware (XIVE controller,
>>> PCI Host Bridges, etc) even if the host is in little endian byte order.
>>
>> Maybe mention commit f7a199b2b44 ("ivshmem: use little-endian
>> int64_t for the protocol")?
> 
> "The protocol" is the interface between ivshmem-doorbell device (client)
> and ivshmem server.  This commit is about the interface between
> ivshmem-* device and the guest.  The two interfaces are about as related
> as SSH and DNS: software exists that uses both.
> 

Yeah, I was about to reply asking what's the relevance of how client-server
communicates and the problem I'm trying to fix. It really seems a problem
with the commit I mentioned in the "Fixes" tag that introduced the memory API
with native endian instead of little endian.

Let's keep the commit msg as is. Thanks,


Daniel


> Mentioning f7a199b2b44 feels superfluous to me.
> 
> [...]
>