Date: Fri, 4 Jun 2004 10:29:46 -0700
From: Paul Jackson <pj@sgi.com>
To: William Lee Irwin III <wli@holomorphy.com>
Cc: mikpe@csd.uu.se, nickpiggin@yahoo.com.au, rusty@rustcorp.com.au,
       linux-kernel@vger.kernel.org, akpm@osdl.org, ak@muc.de,
       ashok.raj@intel.com, hch@infradead.org, jbarnes@sgi.com,
       joe.korty@ccur.com, manfred@colorfullife.com, colpatch@us.ibm.com,
       Simon.Derr@bull.net
Subject: Re: [PATCH] cpumask 5/10 rewrite cpumask.h - single bitmap based
 implementation
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Bill wrote:
> This is patently ridiculous. Make a compat_sched_getaffinity(), and
> likewise for whatever else is copying unsigned long arrays to userspace.

Earlier, Andrew wrote:
> In that case the cpumask code should provide some API function which
> converts a cpumask_t into (and from?) some canonical and documented form. 
> Then you copy what it gave you to userspace.

I'd vote to have the documented form that Andrew speaks of be arrays
of 32-bit words, which is what I understood Mikael was doing.  I agree
with Andrew's suggested to/from canonical functions.

I'd prefer not copying arrays of unsigned longs, due to the confusions
of coding to them across 32/64 bit and big/little endian architectures.
At times I have wished the kernel had chosen u32 arrays instead of
unsigned long arrays for bitmaps, for the same reason.  The cpumask
sprintf and parse format is intentionally 32-bit chunk friendly.

-- 
                          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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