Re: a question regarding <sys/shm.h>


On Wed, 31 Jan 2007, Dag-Erling Smørgrav wrote:

Pascal Hofstee <caelian@xxxxxxxxx> writes:
Any additional sugestions/objections are always greatly appreciated.

On 32-bit platforms (i386, powerpc), int is a 32-bit signed integer while size_t is a 32-bit unsigned integer.

On 64-bit platforms (amd64, sparc64 etc), int is a 32-bit signed integer while size_t is a 64-bit unsigned integer.

In both cases, changing this structure member from int to size_t will break the ABI.

This doesn't mean you shouldn't do it, just that it should be done with care.

If we do decide to go ahead with the ABI change, there are a number of other things that should be done simultaneously, such as changing the uid and gid fields to uid_t and gid_t. I would very much like to see the ABI change happen, and the first step (breaking out kernel from user structures) has been done already as part of the MAC work. The next step is to add routines that translate internal/external formats, which isn't hard, but requires a moderate pile of code to do (as well as great care :-).

Robert N M Watson
Computer Laboratory
University of Cambridge_______________________________________________
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