Re: [PATCH] Linux-2.5 fix/improve get_pid()

[Andries Brouwer <aebr@win.tue.nl>]

On Fri, Aug 09, 2002 at 11:32:33AM +0100, Alan Cox wrote:

> Its much simpler to put max_pid into /proc/sys/kernel. That way we can
> boot with 32000 process ids, which will ensure ancient stuff which has
> 16bit pid_t (old old libc) and also any old kernel interfaces which
> expose it - does ipc ? 

I don't think it is a good idea to add lots of almost meaningless knobs.
This is not something one would like to adapt dynamically.
Someone who needs 16bit pid_t can compile her own kernel with a
suitable value of PID_MAX.

There is no old old libc with 16bit pid_t, I think.
I have libc 4.4.1 here with
	typedef int pid_t;
I have Linux 0.01 here with
	typedef int pid_t;

Yes, ipc exposed pid in a 16-bit field, namely in the fields
msg_lspid, msg_lrpid, shm_cpid, shm_lpid.
Two years ago I found all occurrences in all Linux sources,
but I forgot the details of the result; I do not recall
significant occurrences. Maybe someone will repeat this big grep.

Andries