Comment 43 for bug 264336

I have the same problem in Ubuntu 10.4.

I execute /etc/init.d/postgresql-8.4 start
and the error is:

 * The PostgreSQL server failed to start. Please check the log output:
2010-09-06 09:44:00 CEST FATAL: could not create shared memory segment: Argomento non valido
2010-09-06 09:44:00 CEST DETAIL: Failed system call was shmget(key=5432001, size=37879808, 03600).
2010-09-06 09:44:00 CEST HINT: This error usually means that PostgreSQL's request for a shared memory segment exceeded your kernel's SHMMAX parameter. You can either reduce the request size or reconfigure the kernel with larger SHMMAX. To reduce the request size (currently 37879808 bytes), reduce PostgreSQL's shared_buffers parameter (currently 4096) and/or its max_connections parameter (currently 103).
        If the request size is already small, it's possible that it is less than your kernel's SHMMIN parameter, in which case raising the request size or reconfiguring SHMMIN is called for.
        The PostgreSQL documentation contains more information about shared memory configuration.

At the moment I solved it with this guide:
http://dancingpenguinsoflight.com/2010/03/dealing-with-could-not-create-shared-memory-segment-from-postgres-on-ubuntu/