[U-Boot] Rescue /alternative boot
I would like to have some rescue boot, if flashing of uboot-environment, kernel or filesystem fails. My idea is to check a certain port (eth) for some time and if I receive a defined string not to continue the ususal boot process but execute some into uboot compiled bootcmds. Looking into the code doesn't give me an idea howto do this. Does someone have tried something simular and would share his experience? Thanks Arno
Dear Arno Steffen,
In message AANLkTik0YOONY62q_egSFsTn1nLcQ17yCi_E7bkrief0@mail.gmail.com you wrote:
I would like to have some rescue boot, if flashing of uboot-environment, kernel or filesystem fails.
Why should "flashing of uboot-environment" fail? If you configure for redundant environment, you should always at least have the previous copy of the settings).
As for the rest, kernel and file system, these are application data from U-Boot's point of view, and you can use any method to update these - alternate copies stored in flash and toggled with environment variables, automatic update from USB mass storage devices, automatic updates from TFTP server etc. - Have a look at the manual for details.
My idea is to check a certain port (eth) for some time and if I receive a defined string not to continue the ususal boot process but execute some into uboot compiled bootcmds.
Why inventing another (square?) wheel when there are already several other options available?
Best regards,
Wolfgang Denk
Dear Wolfgang Denk,
thanks for your mail.
2010/6/8 Wolfgang Denk wd@denx.de:
Why should "flashing of uboot-environment" fail? If you configure for redundant environment, you should always at least have the previous copy of the settings).
Right, but what happens if user is doing something stupid? I don't have any connection to uboot at all, as in my final system there is no serial interface to change it back. If linux is not booting anymore I am lost, as this is my only known way to reflash uboot env, kernel, filesystem.
updates from TFTP server etc. - Have a look at the manual for details.
I would see tftpboot as a chance - but there are a few questions to me: - howto call this (and where?) in uboot code? It must be executed before reading the uboot-environment, as this can misconfigured. So it cannot be part of environment. - howto handle boot/kernel parameters? I only know the way via environment variables - the timeout has to set to be very small (as this otherwise in 99% slow down the boot process to much)
This tftpboot look smart - if I could manage this (see above).
Best regards Arno
Dear Arno Steffen,
In message AANLkTinq24UoL7n6J14urGQnxoJOQVpT2FvnJjRgqO-F@mail.gmail.com you wrote:
Why should "flashing of uboot-environment" fail? If you configure for redundant environment, you should always at least have the previous copy of the settings).
Right, but what happens if user is doing something stupid?
Well, you can provide measures for a reset to a sane state, then.
I don't have any connection to uboot at all, as in my final system there is no serial interface to change it back.
You could eventually use netconsole.
If linux is not booting anymore I am lost, as this is my only known way to reflash uboot env, kernel, filesystem.
If just the environment is hosed, it would be sufficient to provide some means to perform a "manufacturer reset" and restore the environment to a known good state. You could - for example - act on certain key presses / key combinations when the board is reset/powered on. Several boards do that.
There has also been discussions for an extension to perform a reset of the envrionment ("env default", if I remember correctly).
Best regards,
Wolfgang Denk
Dear Wolfgang Denk,
Well, you can provide measures for a reset to a sane state, then.
This sounds even more complicated to me. In fact - I don't have any clue, what and howto measure and reset the environment. This system doesn't even had a reset buttom... so it is always a cold boot.
I don't have any connection to uboot at all, as in my final system there is no serial interface to change it back.
You could eventually use netconsole.
Netconsole requires (afaik) a linux kernel, that is working.
If just the environment is hosed, it would be sufficient to provide some means to perform a "manufacturer reset" and restore the environment to a known good state. You could - for example - act on certain key presses / key combinations when the board is reset/powered on. Several boards do that.
I would do so, in fact that was my first idea. But I just have network, nothing else. But here I am at the beginning. How to listen on a network port ( I know what to don in linux, but in uboot?) and howto make this change in uboot environment to a certain state. (this can boot a system via tftp then instead of a flash file system)
Best regards Steffen
Dear Arno Steffen,
In message AANLkTin-oAgoCD6_SK5T-Si9E16-HQdZM-E9F3v2oTKP@mail.gmail.com you wrote:
This sounds even more complicated to me. In fact - I don't have any clue, what and howto measure and reset the environment. This system doesn't even had a reset buttom... so it is always a cold boot.
So how will you find out if there is something wrong, and a reset to a default state is indeed wanted?
You could eventually use netconsole.
Netconsole requires (afaik) a linux kernel, that is working.
We have netconsole support in U-Boot.
But here I am at the beginning. How to listen on a network port ( I know what to don in linux, but in uboot?) and howto make this change in uboot environment to a certain state. (this can boot a system via tftp then instead of a flash file system)
Consider using netconsole then.
Best regards,
Wolfgang Denk
participants (2)
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Arno Steffen -
Wolfgang Denk