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Successful flash but different checksum - any reasons?
Posted: Tue Jan 28, 2003 2:24 am
by changph
Dear Gurus,
Cannot figure this one out. Have successfully hot flashed bios with UNIFLASH. Bios seemed to work ok but when the saved file of the flashed bios is compared to the source the checksum is different?
The flashing included the overwriting of the bootblock of course!
This happened with 2 different bios firmware.
Any explanation for this ?
Regards,
changph
Posted: Tue Jan 28, 2003 10:30 am
by Rainbow
That's because the saved image includes DMI and ESCD (PnP) data. When you first run the BIOS, you see "Verifying DMI Pool Data...Update OK" - BIOS updates the DMI area to match system configuration. So the backup saved after this is of course different.
Posted: Tue Jan 28, 2003 3:11 pm
by KachiWachi
This info is actually saved within the BIOS file? Is it possible to clear it and save that "clean image" somehow...without DMI and ESCD info saved? Why here and not to CMOS memory?
BIOSMan had me do this to help troubleshoot our patching problem...now I understand(?) why...
Posted: Tue Jan 28, 2003 10:41 pm
by Rainbow
The DMI and ESCD data is simply too large (about 4KB each) for CMOS. There were ESCD/DMI manipulating functions (save/restore/clear) in earlier UniFlash versions but they are VERY dangerous. There are no checks if the manipulated area is really ESCD/DMI. Some people killed their BIOSes by using these (I too). DMI is removed, ESCD will be removed in v1.30.
Posted: Wed Jan 29, 2003 3:00 am
by changph
Thank you, guys, for clarifying the puzzle!
Regards,
changph
Posted: Wed Jan 29, 2003 2:54 pm
by KachiWachi
So then when you get a new BIOS update/download from a manufacturer, most likely the DMI/ESCD area is blank, since it has never been loaded to a motherboard...correct??
I guess also that these areas are defined in a particular BIOS as "off limits" so no patching/etc... should be placed there, since it would get overwritten...correct?
Even if there was DMI/ESCD data there, as soon as the BIOS update was complete and the machine rebooted, that data would be replaced with the current state of affairs for you particular board...if all goes well...correct??
Doesn't AWDFLASH have an argument to clear those tables (something tells me it does...since I might have used it)?
Posted: Wed Jan 29, 2003 3:51 pm
by NickS
KachiWachi wrote:Doesn't AWDFLASH have an argument to clear those tables (something tells me it does...since I might have used it)?
/cd /ce
Posted: Wed Jan 29, 2003 8:10 pm
by KachiWachi
Thought so...
So are the AWDFLASH commands any safer then those from UNIFLASH?
Posted: Wed Jan 29, 2003 9:15 pm
by Rainbow
If Awdflash is used with Award BIOS, it should know if the area really contains ESCD/DMI data. UniFlash clears specific size at specific address which results sometimes in clearing a part of code...
Posted: Thu Jan 30, 2003 1:17 am
by KachiWachi
I wonder what makes AWDFLASH so smart then (how it knows)...and what if you have patched your BIOS...will it still be as smart?
I would assume something in the BIOS code tells where the off-limits areas are (since it has to write the information there in the first place). Can/does AWDFLASH read that info from the BIOS code...is that how it knows?
I would guess making a "Universal Flasher" would present problems for that then...so much to know...or at least a really "fat" program...
Posted: Thu Jan 30, 2003 12:01 pm
by Rainbow
I think that the DMI/ESCD manipulating is useless. BIOS updates that on reboot when there's something incorrect there.
