Shared memory problems under SVr2

[Frank Mayhar]

In article <May.28.09.29.06.1988.25821 at topaz.rutgers.edu> ron at topaz.rutgers.edu (Ron Natalie) writes:
>Can't say I can fix your problem, but I can suggest what we did.
>Get a better SCSI controller.  [...]

Well, we figured out what was wrong, and it was a bug in Motorola's version 2.2
of SVR2.  When I looked at the mmu_entry for the affected process with crash,
I noticed that the p_addr for the shared memory segment was zero.  So yesterday
we traced the shmget() code to figure out where to get the right p_addr (from
the page table for that shared memory area).  We're kludging around the problem
by using an ioctl() into our SCSI driver to fill in the proper physical address
in the mmu_entry (we do the ioctl() _after_ the shmat()), by tracing down the
page table tree.  Apparently, this problem is fixed in version 3.0.  Since it
only affects doing I/O directly from shared memory, everything else worked
properly.  Tuesday we get to test our kludge.  Please wish us luck!

Thanks for the couple of responses!
-- 
Frank Mayhar            UUCP: ..!{ihnp4,dj3b1}!killer!fmayhar
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