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SubjectRe: Linux 2.3.39 has 32bit uid. What about 32bit pid?
In <85t517$1o4$1@penguin.transmeta.com> Linus Torvalds (torvalds@transmeta.com) wrote:
> In article <UTC200001152131.WAA07579.aeb@arend.cwi.nl>,
> <Andries.Brouwer@cwi.nl> wrote:
>>
>> No, its worse sadly -- think fcntl(fd,F_SETOWN,&pid) sort of thing.
>> We will need a new F_SETOWN or esle the SIGIO stuff will break.
>>
>>But where is the problem?
>>Let me repeat: pid_t has *always* been 32-bit.
>>In libc5. In libc4. In Linux 0.01.

> Indeed.

> In fact, I think that in Linux 0.01 it actually _used_ all bits.

> I remember how I was chasing a strange bug in bash, which turned out to
> be because _bash_ used "short" somewhere to store a pid. And this was
> long long before Linux development and me became arrogant enough to say
> "oh, bash is broken, tell Chet to fix it", so what I ended up doing was
> to just make sure that yes, "pid_t" was still 32-bit, but we only ever
> selected pids in the 15-bit range.

> We could start using 32-bit pid's any day, but for (a) /proc and (b) I'm
> not sure what makes sense in a cluster. Do we want to have the high bits
> be just high bits, or do we want them to be cluster machine ID, or do we
> want them to be thread-ID related?

> So the dynamic range of pids stays at 15 bits until it's clear what the
> right thing is. The type stays at 32 bits..

Do this mean that ipc_pid_t will be extended ?

> Linus




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