On Mon, Sep 17, 2018 at 10:59 PM, Chris Murphy <li...@colorremedies.com> wrote:
> Hi,
>
> GRUB code can certainly read files that are on Btrfs, md devices,
> LUKS, LVM, and so on. But GRUB code can also write to the physical
> block for grubenv - but are there safe guards that prevent it from
> doing so if grubenv is on something like Btrfs, mdadm raid5, LUKS?
>
> And also what about XFS? This used to be safe, but now with reflink
> support, grubenv could be reflink copied, meaning any overwrite is
> disallowed and must be COW'd. How is that handled?
>
> I'm pretty sure on Btrfs GRUB knows is can't write to grubenv, I'm
> just curious about the other cases.
OK so it allows me to create a grubenv on Btrfs without any complaint.
Will the bootloader actually try to write to this if grub.cfg contains
save_env?
$ sudo grub2-editenv --verbose grubenv create
[sudo] password for chris:
[chris@f29h ~]$ ll
-rw-r--r--. 1 root root 1024 Sep 18 13:37 grubenv
[chris@f29h ~]$ stat -f grubenv
File: "grubenv"
ID: ac9ba8ecdce5b017 Namelen: 255 Type: btrfs
Block size: 4096 Fundamental block size: 4096
Blocks: Total: 46661632 Free: 37479747 Available: 37422535
Inodes: Total: 0 Free: 0
[chris@f29h ~]$
--
Chris Murphy
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