Miniscule SHMMAX causing trouble

[John Goerzen <jgoerzen@complete.org>]

I have been trying out the "buffer" program.  This thing can make use of a
lot of shared memory.  Unfortunately, it was not working for me.  Martin
Buck, the Debian developer that I wrote to about it, pointed this out:

wallace:$ grep '#define SHMMAX' /usr/local/src/linux-2.0.34/include/asm-alpha/shmparam.h 
#define SHMMAX 0x3fa000                 /* max shared seg size (bytes) */
               ^^^^^^^^
whereas:

wallace:~$ grep '#define SHMMAX' /usr/local/src/linux-2.0.34/include/asm-i386/shmparam.h 
#define SHMMAX 0x2000000                /* max shared seg size (bytes) */
               ^^^^^^^^^

Now, I am indeed on Alpha.  Why is the maximum shared memory size on Alpha
miniscule like that?  Certainly a 64-bit machine should be able to use at
least as much shared memory as a 32-bit one!

Is this something that I can tweak and set to an arbitrary value?

This problem is in all the way from 2.0.x to 2.2.0pre.

Thanks,
John