Re: [Qemu-devel] [PATCH 0/7] Fix packing for MinGW with -mms-bitfields

[Blue Swirl]

On Sun, Aug 28, 2011 at 8:43 PM, Stefan Weil <address@hidden> wrote:
> These patches fix the packing of structures which were affected by
> the new compiler attribute -mms-bitfields (which is needed for glib-2.0).
>
> I compiled qemu.exe with and without -mms-bitfields and compared
> the resulting struct alignment using pahole and codiff.

If a structure is only used internally by QEMU (not used in network,
disk or guest interfaces), changes in padding don't matter. In fact,
in those cases it may be better to remove the packing, because then
the fields may be naturally aligned and that gives better performance
on most architectures. Could you please check if this is the case for
any of the structs?

> The patches are split for different maintainers.
> Feel free to combine them on commit.
>
> I suggest replacing the remaining code with __attribute__((packed))
> or __attribute__((__packed__)) in separate patches.
>
> Cheers,
> Stefan
>
> [PATCH 1/7] Add new macro QEMU_PACKED for packed C structures
> [PATCH 2/7] block/vvfat: Fix packing for w32
> [PATCH 3/7] acpi: Fix packing for w32
> [PATCH 4/7] hpet: Fix packing for w32
> [PATCH 5/7] usb: Fix packing for w32
> [PATCH 6/7] virtio: Fix packing for w32
> [PATCH 7/7] slirp: Fix packing for w32
>
>
>