Re: [PATCH] hw/usb: Use __attribute__((packed)) vs __packed

[Michael Tokarev <mjt@tls.msk.ru>]

04.11.2024 10:37, Thomas Huth wrote:
> On 01/11/2024 22.17, Roque Arcudia Hernandez wrote:
>> __packed is non standard and is not present in clang-cl.
>> __attribute__((packed)) has the same semantics.
>>
>> Signed-off-by: Erwin Jansen <jansene@google.com>
>> Signed-off-by: Roque Arcudia Hernandez <roqueh@google.com>
>> ---
>>   include/hw/usb/dwc2-regs.h | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/hw/usb/dwc2-regs.h b/include/hw/usb/dwc2-regs.h
>> index 523b112c5e..b8b4266543 100644
>> --- a/include/hw/usb/dwc2-regs.h
>> +++ b/include/hw/usb/dwc2-regs.h
>> @@ -838,7 +838,7 @@
>>   struct dwc2_dma_desc {
>>           uint32_t status;
>>           uint32_t buf;
>> -} __packed;
>> +} QEMU_PACKED;
> 
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> 
> Actually, the struct only consists of two 32-bit values, so I doubt that the "packed" is needed here at all. Maybe we could even simply remove it?
To me it is important to mark structures as packed if it is
important for them to have strict layout like in this case,
even if de-facto it does not change the actual layout.  It's
just like an annotation saying this structure can be used
on wire or somesuch.

/mjt