Setting shared buffers

After checking some docs on performance tuning, I'm trying to
follow Bruce Momjian (sp??) advice to set the shared_buffers
at 25% of the amount of physical memory (1GB in our server)
and 4% for the sort_mem.

When I try that, I get an error message when starting postgres,
complaining that the amount of shared memory requested exceeds
the maximum allowed by the kernel (they talk about increasing
the kernel parameter SHMMAX -- does this mean that I have to
recompile the kernel? Or is it just a "runtime" configuration
parameter that I set and on the next reboot will be taken?)

To double check if I understood correctly:

I have 1GB, so I want 256MB as shared buffers memory; each
shared buffer is 8kbytes, so I take 256M / 8k, which is 32k --
so, I uncomment the line shared_buffers in the configuration
file, and put:

shared_buffers = 32000

I don't touch anything else (max_connections keeps its default
value, but as I understand, that has nothing to do anyway...
right?)

So, what should I do?

Apologies if this is an FAQ -- I tried searching the archives,
but I get a 404 - Not Found error when following the link to
the archives for this list :-(

Thanks in advance for any comments / advice !

Carlos
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