Date: Sun, 6 Jun 2004 05:16:57 -0700
From: Paul Jackson <pj@sgi.com>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: wli@holomorphy.com, mikpe@csd.uu.se, linux-kernel@vger.kernel.org,
       akpm@osdl.org
Subject: Re: [PATCH] cpumask 5/10 rewrite cpumask.h - single bitmap based
 implementation
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Rusty wrote:
> Yes, NR_CPUS needs to get to userspace somehow sanely if we want to fix
> this in general.

Are you saying that NR_CPUS is needed, or just the number of longs in a
cpumask (sizeof (cpumask_t), essentially)?

I can see where the size is needed, in order to make the system calls to
set and get masks of arbitrary size.  Since these sizes are a multiple
of sizeof(long), at a minimum this means user code needs to know the
number of longs in a mask.  Though the number of bytes, as in
sizeof(cpumask_t), rather than of longs, is perhaps a less surprising
interface.

I can't see where the user code cares whether NR_CPUS is 47 or 48?

Am I missing something?

I am a firm believer in passing the minimum essential information across
major boundaries.  Passing too much creates maintaince problems, and
encourages misuse of information, resulting in bogus user code.

-- 
                          I won't rest till it's the best ...
                          Programmer, Linux Scalability
                          Paul Jackson <pj@sgi.com> 1.650.933.1373
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