Hi there developers,
I posted this message last night and I was wondering if one of you would be kind enough to make a reply as to your assessment of having an LVM write function implemented. I am in dire need to have this capability so I'm willing to code myself if need to. I just need to understand the pitfalls and get an idea of the amount of time and work to implement it. I have looked at the grub_lvm_read and it appears to have all the necessary logic to decode the lvm format. I was thinking of reusing that code and at the end of it simply do a disk->dev->write which should invoke the underlying hard disk write routine (I'm new to grub2 so this is my understanding from a quick parse of the code).
Any help is extremely appreciate it... even if it
is a short message to say my idea doesn't work because...
Thanks
R.
Date: Mon, 9 Nov 2009 17:11:53 -0800 (PST)
From:
Roger Cruz <
address@hidden>
Subject: LVM write support from grub2. Writing to environment block in
core.img
I
have a system where the boot partition is on top of an LVM. I'm using
the loadenv module to save state and remember the previously booted
entry. I have something like this:
if [ ${prev_saved_entry} ];
then saved_entry=${prev_saved_entry} save_env saved_entry
prev_saved_entry= save_env prev_saved_entryfi
In examining why save_env is not writing to grubenv, I came across this LVM routine that says LVM writes are not supported.
static grub_err_t
grub_lvm_write (grub_disk_t disk __attribute ((unused)),
grub_disk_addr_t sector __attribute ((unused)),
grub_size_t size __attribute ((unused)),
const char *buf __attribute ((unused)))
{
return GRUB_ERR_NOT_IMPLEMENTED_YET;
}
Is
there a plan to add this support? Anyone currently working on it that
I may get an early implementation from? If not, is there a technical
reason why this would be hard for someone (maybe me) to implement?
As
a work-around, I'm considering using the environment block in
core.img. Are there routines that can be run at boot time to allow
grub to change the variables there, perhaps using the same module
(loadenv) and so it can be used as "save_env -f core.img"? Anyone see
any reasons why I shouldn't write to that space?
Thanks
Roger