Xref: utzoo comp.unix.internals:2138 comp.unix.wizards:24224 Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!chinacat!sequoia!rpp386!jfh From: jfh@rpp386.cactus.org (John F Haugh II) Newsgroups: comp.unix.internals,comp.unix.wizards Subject: Re: Help with 4.3 mod to kill uninteruptable procs. Message-ID: <19067@rpp386.cactus.org> Date: 22 Feb 91 04:50:38 GMT References: <1991Feb19.001941.29928@lynx.CS.ORST.EDU> <4066@stl.stc.co.uk> <19065@rpp386.cactus.org> <1991Feb21.145705.27763@cbnews.att.com> Reply-To: jfh@rpp386.cactus.org (John F Haugh II) Organization: Lone Star Cafe and BBS Service Lines: 17 X-Clever-Slogan: Recycle or Die. In article <1991Feb21.145705.27763@cbnews.att.com> rock@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@rpp386.cactus.org "I've never written a device driver, but I have written a device driver manual" -- Robert Hartman, IDE Corp. Brought to you by Super Global Mega Corp .com