Messages in this thread | | | From | Keith Owens <> | Subject | Re: [PATCH] nodemask_t x86_64 changes [5/7] | Date | Mon, 29 Mar 2004 15:08:46 +1000 |
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On Thu, 25 Mar 2004 23:14:12 -0800, Paul Jackson <pj@sgi.com> wrote: >Does your way work if NR_CPUS is less than BITS_PER_LONG? >Won't gcc complain upon seeing something like, for say >NR_CPUS = 4 on a 32 bit system: > > { [ 0 ... -1 ] = ~0UL, ~0UL << 28 } > >with the errors and warnings: > > error: empty index range in initializer > warning: excess elements in struct initializer
I only did one case, to concentrate on the value for the last word. A full implementation has to cater for NR_CPUS < BITS_PER_LONG as well.
>and shouldn't the last word be inverted: ~(~0UL << NR_CPUS_UNDEF) ?
For big endian, ~0UL << NR_CPUS_UNDEF is right. For little endian, it depends on how you represent an incomplete bit map. Is it represented as a pure bit string, i.e. as if the arch were big endian? Or is it represented as a mapping onto the bytes of the underlying long?
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