[U-Boot] [POST] retrieving the results in Linux ?
Hello,
In the POST documentation, it is clearly stated:
- The results of tests shall be saved so that it will be possible to retrieve them from Linux.
I have two questions here:
- I don't find where the result actually is saved. Was this implemented already ? Was the logbuffer intented for this (call to logbuff_log in post_log) ?
- If I was wrong for the first question (the results actually are saved), where can I find some information about how to retrieve these results ?
Dear Valentin Longchamp,
In message 4E146E9F.4000705@keymile.com you wrote:
In the POST documentation, it is clearly stated:
- The results of tests shall be saved so that it will be possible to retrieve them from Linux.
I have two questions here:
- I don't find where the result actually is saved. Was this implemented already
? Was the logbuffer intented for this (call to logbuff_log in post_log) ?
Yes. The idea is to share the log buffer between U-Boot and Linux (hence it's allocation at the very end of the RAM). Of course you need support for this feature in Linux, too. IIRC this has not yet made it's way into mainline.
- If I was wrong for the first question (the results actually are saved), where
can I find some information about how to retrieve these results ?
The plan is to share the log buffer, in both directions: Linux can read the POST results, and U-Boot can read the last Linux messages after a crash / reboot. Actually, after a reboot you can read the last messages from the _previously_ running kernel in Linux, too (assuming there are no wraparounds, of course).
Best regards,
Wolfgang Denk
Le 06/07/2011 23:25, Wolfgang Denk a écrit :
The plan is to share the log buffer, in both directions: Linux can read the POST results, and U-Boot can read the last Linux messages after a crash / reboot. Actually, after a reboot you can read the last messages from the _previously_ running kernel in Linux, too (assuming there are no wraparounds, of course).
Even with wraparounds, you could still be able to read the last messages; only overwrites would prevent it.
Best regards,
Wolfgang Denk
Amicalement,
Dear Albert,
In message 4E15DCD4.7000608@aribaud.net you wrote:
The plan is to share the log buffer, in both directions: Linux can read the POST results, and U-Boot can read the last Linux messages after a crash / reboot. Actually, after a reboot you can read the last messages from the _previously_ running kernel in Linux, too (assuming there are no wraparounds, of course).
Even with wraparounds, you could still be able to read the last messages; only overwrites would prevent it.
Well, what I meant was: when the new kernel produces enough boot messages to cause a wrap-around of the log buffer, then all traces of the previous kernel's messages will be lost.
Best regards,
Wolfgang Denk
participants (3)
-
Albert ARIBAUD -
Valentin Longchamp -
Wolfgang Denk