Did you look at cpio generation facility in initrd command? This may be what your are looking for
On Mon, 28 Oct 2019, 03:59 Max Tottenham via Grub-devel, <grub-devel@gnu.org> wrote: > Hi Folks > > I've often found myself in a position where I've needed to perform some > debugging of remote hardware that does not have a network accessible KVM > attached. To that end, being able to remotely log into a machine and > have some method of accessing GRUB2 boot time debug messages from > userspace (in my case linux), would be rather useful. It also dawned on > me that this capability might be the sort of thing that folks upstream > might be keen on. > > I have done a little thinking and have thought of two possible > approaches: > > > 1. Perform some hacking of the grub environment block (load/save env) > handling to be able to write log data to either the same file in /boot, > or perhaps a separate distinct debug log file. > > 2. Export the debug log to a running kernel as another initrd image. In > other words, have GRUB2 buffer a bunch of log messages and then append > that log data as a separate initrd archive. Some early userspace program > would then be able to copy that archive to the real filesystem, or > stick it into the kernel log buffer. The logfile in the > initrd that GRUB generates could have either a configurable name based > on some setting in grub.cfg, or some well known default name (like > /grub2-debug.log) > > > I initially started with 1, but I dislike the approach of having GRUB2 > write to the filesystem, it's also a little cumbersome to setup, > > > Approach 2 seems like it would work (at least for linux, I've no > experience with the BSDs but presumably any OS that can load multiple > initrd's would be able to use this approach too), and has the advantage > that it doesn't have to touch any data on disk. > > If there is no objection I can whip up a POC patch for 2 and post it to > the list? > > Regards > > -- > Max Tottenham | mtott...@akamai.com > Senior Software Engineer, Server Platform Engineering > /(* Akamai Technologies > > _______________________________________________ > Grub-devel mailing list > Grub-devel@gnu.org > https://lists.gnu.org/mailman/listinfo/grub-devel >
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