Messages in this thread | | | Date | Sat, 10 Jul 1999 17:14:16 -0700 (PDT) | From | Dan Hollis <> | Subject | Re: KMSGDUMP: dump kernel messages to a diskette |
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On Sat, 10 Jul 1999, Willy Tarreau wrote: > Concerning the possibilities of executing code upon a manual reset, I've > tested it and it doesn't work. The PC simply reboots. I remember that some > chipsets clean all the memory themselves upon reset. But what I can't > understand is why the bios doesn't hang instead of rebooting. Since my > CMOS register contains 0xA or 0x9 or anything else, the bios should notice it.
I have done some investigation and it seems that at least on Award BIOS, the "quick post"/"quick power on selftest" option in BIOS causes the BIOS to skip memory testing. Possibly this leaves RAM untouched after a hard reset.
So another possibility is to have a "clean/dirty" flag at the top of RAM, similar to what is used for mounted filesystems. If the OS cleanly shuts down, this flag is set "clean", it indicates it was a clean shutdown and no crashdump is needed. If it is left "dirty", then lilo can do a memory dump to the swap partition, which is then picked up by 'swapon' and written to the filesystem.
-Dan
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