Re: [RFC][PATCH] 2/6 POSIX message queues

[Manfred Spraul]

Arnd wrote:

> Nothing difficult here, but slow and avoidable if you have the
> structures laid out properly.
I thought about using s32 for the kernel mq_attr structure, and didn't 
like it: It would mean that 64-bit archs running native 64-bit apps must 
do a conversion - glibc must expose a structure with long values.
Additionally, the posix message queue API uses 3 structures with long 
values, and only one of them is new - we'll need wrappers anyway.
The actual values in the mq_attr structure would fit into s32:
- mq_flags is 0 or O_NONBLOCK
- mq_maxmsg is less than 32k (kmalloc'ed array of pointers)
- mq_msgsize is theoretically unlimited, but the current implementation 
arbitrarily limits the value to 1 MB.

--
   Manfred


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