This avoids compilers detect misaligned access which can lead to
warnings.
In QEMU the structure is allocated at the beginning of a 4Kb page,
in Xspice is allocated with a calloc, so the structure will end up 4
bytes aligned as well with these users. We are not aware of other users
of QXLRam, but if there was, it's likely the struct would be at least
naturally aligned, so this change should not impact anyone.
Aligning to 4 bytes maintains the size of the structure unchanged
avoiding possible ABI changes.
clang currently generates an invalid function call if a misaligned
4 byte atomic operation is detected.
This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1565766
Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
Acked-by: Christophe Fergeau <cfergeau@redhat.com>
Ex: G_STRUCT_OFFSET(SpiceLinkReply, num_channel_caps) is 172 bytes
when compiled with -mms-bitfield, and 170 bytes without.
GLib/Gtk are compiled with -mms-bitfield, and it is necessary to
compile with the same option for compatibility. The pack pragma
for MINGW32 corrects the structure alignement.
We could use the pack pragma for GNUC unconditionally, that could help
to ensure struct binary compatibility between different compiled
flavours.
