Re: [Xen-devel] [PATCH] x86/EFI: define and use EFI_DIR make variable, defaulting to /usr/lib64/efi

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2012-07-23 at 11:03 +0100, Jan Beulich wrote:
> >>> On 23.07.12 at 11:35, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Mon, 2012-07-23 at 10:07 +0100, Jan Beulich wrote:
> >> >>> On 23.07.12 at 10:43, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> >> > What is this stuff installed in /usr/lib*/efi anyway? I suppose it isn't
> >> > boot time stuff (which should go in /boot or /boot/efi). 
> >> 
> >> It *is* boot time stuff, and is does *not* belong into /boot.
> >> When putting this together, I was told that the EFI partition
> >> has to be considered volatile (i.e. may get destroyed and
> >> re-created at any time).
> > 
> > Do you have a reference for this?
> 
> Not readily; I could ask the person who told me.
> 
> > OOI what is /boot/efi for if it can be regenerated at any time?
> 
> To boot the system. As this is using the old FAT file system, it's
> not really reliable in case of kernel crashes and could be
> re-initialized from the EFI shell of other firmware management
> operations, and hence shouldn't be used for any non-volatile data.

So /boot/efi is effectively a /tmp style thing for the EFI shell?

> >>  This is why elilo.efi also has its real
> >> home under /usr, not under /boot/efi.
> > 
> > I noticed that (at least on Debian) grub uses /usr/lib/grub/<arch>-efi
> > and elilo uses /usr/lib/elilo.
> 
> It's definitely /usr/lib64/efi/elilo.efi on SLE11, so I'm afraid this
> really ins't well standardized (and hence an EFI_DIR override is
> warranted, yet settling on a proper default may be problematic).
> 
> > Does that mean we should be using /usr/lib/xen/efi rather than /usr/lib/efi?
> > 
> > What is the policy for EFI install location on RPM/LSB based systems?
> 
> Don't know.

I think LSB basically #includes FHS for this but even the FHS 3.0 drafts
don't seem to mention EFI (at least not in a greppable way).

> 
> >> > We already have EFI_MOUNTPOINT under xen/*, I think EFI_DIR under there
> >> > (or in config/*) is fine also.
> >> 
> >> That part wasn't controversial (if generally useful), but imo it
> >> shouldn't expand to an open-coded path (unless put into
> >> config/x86_64.mk).
> > 
> > I could live with that. Unlike LIBDIR, where getting it wrong can mean
> > things don't work, getting EFI_DIR wrong is merely ugly.
> 
> Not exactly - it might still mean that boot loader installation (and
> update) doesn't work anymore.

At worst it'll just fail to include Xen, won't it? Installing Xen to the
wrong directory shouldn't effect any other EFI bootloader, I would
hope...

>  But getting things consistent
> would be a one-time per-distro task, so ought to be manageable.

Right.

Ian.



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