You are correct... We have no battery backup on our custom carrier board. Bill
-----Original Message----- From: Michael Karcher [mailto:flashrom@mkarcher.dialup.fu-berlin.de] Sent: Thursday, April 08, 2010 12:44 AM To: Carl-Daniel Hailfinger Cc: Bill Flanders (wtflanders); flashrom@flashrom.org Subject: Re: [flashrom] JIDA CMOS
Am Donnerstag, den 08.04.2010, 04:20 +0200 schrieb Carl-Daniel Hailfinger:
I ran into the same problem when I automated flashing the BIOS followed by running nvramtool to set the CMOS values. The settings do not hold if you power down the system, however, they do hold when you reboot the system via the "reboot" command.
So unless I'm misunderstanding you, the BIOS performs some "magic" on a warm reboot which causes the effect of nvramtool to become permanent.
As I understand it, the system is equipped with two storage system for the BIOS parameters: The CMOS RAM/"RTC" and an "EEPROM" (which is why you need to run jidacmos twice - one for rtc, once for eep). My guess would be that this eeprom is a i2c eeprom that contains a copy of the rtc parameters. The CMOS RAM seems to be powered down/lose settings on powering down the system (i.e. no battery backup), so parameters are restored from the EEPROM on next power-on.
Regards, Michael Karcher