Help with 4.3 mod to kill uninteruptable procs.

[John F Haugh II]

In article <1991Feb21.145705.27763 at cbnews.att.com> rock at cbnews.att.com (Y. Rock Lee) writes:
>Forcibly awaking a process doing read/write (DMA transter) will either
>give the process a buffer with garbage data or throw away a buffer
>containing valid data. How can this trash someone else's memory?

DMA addresses typically refer to physical memory.  The process requesting
the DMA transfer normally is locked in memory before the transfer is
requested so that the physical address the controller was told to send
the data to will remain valid.  If the process dies and the physical
memory is reallocated (or page out or swap out or ... occurs), that
physical address will be allocated to some other process which isn't
expecting to have your DMA transfer sent its way.
-- 
John F. Haugh II                             UUCP: ...!cs.utexas.edu!rpp386!jfh
Ma Bell: (512) 832-8832                           Domain: jfh at rpp386.cactus.org
"I've never written a device driver, but I have written a device driver manual"
                -- Robert Hartman, IDE Corp.