[PATCH] 0/2 RFC: yaboot --bootonce

Judith Lebzelter judith at osdl.org
Tue Jan 9 04:48:46 EST 2007


This patch set (described below) was put out in September, but there 
were a few unanswered questions.  I was wondering whether this feature 
had made any progress as I would find it very useful.

Judith Lebzelter

On Mon, 18 Sep 2006 17:07:15 CDT, Dustin Kirkland wrote:
>Often when building and testing kernels, one wants to boot a specific
>kernel in an unattended manner.  Changing the default kernel in the
>bootloader configuration file fulfills this purpose, however, it creates
>a problem when the newly booted kernel is buggy or does not boot.
>Ideally, one would be able to specify to the bootloader that a
>particular kernel is to be booted once on the very next boot, but
>subsequent boots would revert back to the default kernel behavior
>specified in the bootloader configuration file.
>Other Linux bootloaders provide this functionality in one way or
>another.  In the automated Linux testing space, we have a need for
>Yaboot to provide this functionality for our PPC platforms in an
>unattended manner.
>The following patch set is submitted as a Request for Comments in that a
>small bit of functionality is still missing and I could use some
>assistance with that piece.
>The design is as follows:
>- 1/2: In userspace, extend ybin to understand a --bootonce parameter,
>which takes a bootloader entry label.  If this is an existing, valid
>label in the bootloader configuration file, perform a raw write of that
>value to an empty block in the PReP boot partition.
>- 2/2: In bootloader-space, extend the 'default' kernel determination to
>first examine the reserved block in the PReP boot partition for bootonce
>information.  If a valid bootloader entry label is found there, use that
>label as the 'default' entry for this boot, and zero out the data in
>that block so as to not affect subsequent boots.

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