On 06/24/00 19:24:49 +0100 Tigran Aivazian <tigran@veritas.com> wrote:
+-----
| > They should be fixed to use __attribute__((packed)). Also they
| shouldn't > have any unaligned struct members.
|
| are you 100% sure its needed? So all filesystems should use
| __attribute__((packed)) when they describe on-disk inode/superblock
| layout? none of the existing ones (except, partially, ncpfs) do.
+--->8
De facto, for most if not all Linux-supported architectures, if you put
larger members before smaller members, gcc won't add padding; also, if you
do something like
u32 a;
u16 b1;
u16 b2;
u32 c;
no padding will be added because b1 and b2 leave the structure aligned
properly.
You can continue to rely on this; or you can use __attribute__((packed))
and be certain that it will work correctly on any future architectures with
"unusual" alignment requirements. (Personally, I don't really expect to
see many of the latter --- but I'm no architecture guru, and for all I know
it may be the wave of the future.)
--
brandon s. allbery os/2,linux,solaris,perl allbery@kf8nh.apk.net
system administrator kthkrb,heimdal,gnome,rt,cyrus allbery@ece.cmu.edu
carnegie mellon / electrical and computer engineering kf8nh
We are Linux. Resistance is an indication that you missed the point.
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