Dear all: I was puzzled by the fallback and normal image in s2722 (e7500), I am sorry to ask so simple question. When shall we use the fallback image and when shall we use the normal image? How you control which to run? The register DRC (7c) bit 29(Init complete) seem not to be set after memory initialization complete. am I right? Thank you!
Greetings,
Several conditions need to exist for the primary image to be used. The code looks at the RTC register to check for indication of power failure (either battery dead, or clear CMOS jumper set), then the CMOS checksum is checked. If both tests show that CMOS is valid, then check the RTC_BOOT_BYTE. First, bit 0 is moved to bit 1 and bit 0 is cleared. Then, if bit 1 is set, call the primary (normal image), That is done so that if the boot fails for some reason, it will choose the fallback image next time. It is also possible to cause a fallback boot by setting the clear CMOS jumper.
The RTC_BOOT_BYTE is not included in the checksum since it will be changed wi8th every boot.
Note that on some boards, the CMOS checksum is skipped.
G'day, sjames
The RTC_BOOT_BYTE
On Thu, 20 Feb 2003, Terry B. Chen wrote:
Dear all: I was puzzled by the fallback and normal image in s2722 (e7500), I am sorry to ask so simple question. When shall we use the fallback image and when shall we use the normal image? How you control which to run? The register DRC (7c) bit 29(Init complete) seem not to be set after memory initialization complete. am I right? Thank you!
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steven james -
Terry B. Chen