Re: *** ANNOUNCEMENT *** LVM 0.9.1 beta1 available at www.sistina.com

Anton Blanchard (anton@linuxcare.com.au)
Sat, 13 Jan 2001 14:00:58 +1100



Hi,

> What is the reason for all this? Alignment/wordsize/other? If you look
> at the IOP10 code, much of the in-core data structs were changed to int
> or long, so this sparc code may not be necessary. It may in fact be
> damaging, because I don't know if any of the LVM developers even know it
> is there, and surely it will be out of sync...

Two things:

Structures used in ioctls should have explicit sizes (eg u32, not unsigned
long). Remember on sparc64 we have a 32 bit userspace and 64 bit kernel.

Having pointers to other structures is considered bad form again due to the
32bit/64bit differences. Think 32 bit pointers vs 64 bit pointers :)

When either of these happen we have to write up translation code. Of
the two, having pointers to other structs is definitely the worst.

Anton
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