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Re: User-settable FD_SETSIZE and select()
- From: mtk-lists at gmx dot net
- To: libc-alpha at sources dot redhat dot com
- Date: Tue, 20 May 2003 11:52:03 +0200 (MEST)
- Subject: Re: User-settable FD_SETSIZE and select()
- References: <20030520073339.GA22793@suse.de>
[This is a possble duplicate, since I think I failed to include the
list on an earlier send of this message]
> On Tue, May 20, firstname.lastname@example.org wrote:
> > > Use poll().
> > This does make it harder to port applications using select() from other
> > implementations which allow higher limits for FD_SETSIZE. E.g., HP/UX
> > has a limit of 2048, and Tru64 has 4096. And while the default limit os
> > 1024 on Solaris, I seem to recall it can be raised.
> > > FD_SETSIZE will not be changed, it's not binary compatible.
> > I'm not sure what you are meaning here -- "not binary compatible" with
> With existing binaries.
> > As I noted, manually editing the current glibc header files allows
> > to use higher FD_SETSIZE values without the need for either a Linux
> > rebuild or a glibc rebuild.
> Change FD_SETSIZE, recompile glibc or an application using RPC
> and use excessive RPC applications and portmap. You will get a lot
> of mysterious errors.
Thanks for your note. Maybe I'm being slow. What is to stop one
having something like:
#define FD_SETSIZE __FD_SETSIZE
(or some such, I assume you get the drift), so that applications
that want it can do a "cc -DFD_SETSIZE=n". This doesn't require
a glibc recompilation, and should therefore not effect the RPC stuff
(since it doesn't attempt to redefine FD_SETSIZE). Or am I
missing something still?
Really, all I'm looking for is a simple way of changing the idea that
FD_ZERO() has of the size of an fd_set. (FD_ZERO is the only one
of the FD_*() macros that depends on size of an fd_set.) As I said,
the Linux kernel already handles larger set sizes (it derives its info
from the first argument of select()).
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