[PATCH v5 3/8] bootstd: Support booting EFI where multiple options exist

[Simon Glass]

Hi Tom,

On Thu, 6 Apr 2023 at 02:48, Tom Rini <trini at konsulko.com> wrote:
>
> On Wed, Apr 05, 2023 at 05:28:07PM +1200, Simon Glass wrote:
> > Hi Tom,
> >
> > On Tue, 4 Apr 2023, 02:17 Tom Rini, <trini at konsulko.com> wrote:
> >
> > > On Mon, Apr 03, 2023 at 12:56:49PM +0300, Ilias Apalodimas wrote:
> > > > On Sat, Apr 01, 2023 at 07:31:49PM +1300, Simon Glass wrote:
> > > > > Hi Tom,
> > > > >
> > > > > On Sat, 1 Apr 2023 at 07:02, Tom Rini <trini at konsulko.com> wrote:
> > > > > >
> > > > > > On Fri, Mar 31, 2023 at 10:25:56AM +1300, Simon Glass wrote:
> > > > > >
> > > > > > > The current EFI implementation has a strange quirk where it watches
> > > > > > > loaded files and uses the last-loaded file to determine the device
> > > that
> > > > > > > is being booted from.
> > > > > > >
> > > > > > > This is confusing with bootstd, where multiple options may exist.
> > > Even
> > > > > > > loading a device tree will cause it to go wrong. There is no API
> > > for
> > > > > > > passing this information, since the only entry into booting an EFI
> > > image
> > > > > > > is the 'bootefi' command.
> > > > > > >
> > > > > > > To work around this, call efi_set_bootdev() for EFI images, if
> > > possible,
> > > > > > > just before booting.
> > > > > > >
> > > > > > > Signed-off-by: Simon Glass <sjg at chromium.org>
> > > > > >
> > > > > > Shouldn't this all be a simple wrapper around the EFI Standard
> > > > > > BootDeviceOrder or whatever that's called?
> > > > >
> > > > > I think you are referring to boot manager, which isn't used here. This
> > > > > is replicating the existing distroboot functionality in standard boot.
> > > >
> > > > The distroboot functionality *was* trying to behave like the EFI spec
> > > > expects the bootmanager to behave.  Unfortunately I haven't had time to
> > > > review the distroboot patches closely, but back when this started, my
> > > point
> > > > was that EFI doesn't need anything.  Whenever the EFI flow is added
> > > bootstd
> > > > should 'just' call the bootmanager.
> > >
> > > Yes, this. We're trying make things cleaner overall, so the EFI portion
> > > of bootstd distro boot should just be "call EFI bootmanager" as that has
> > > a well defined standard way to specify what devices to try in what
> > > order.
> > >
> >
> > We already call bootmgr in standard boot, if it is enabled.
> >
> > But I am not sure how widely that is used...
> >
> > This patch is about corner cases in the distro scripts. If we are to turn
> > these down we do need to try to do the same thing.
>
> We probably need some distro people to chime in about what they're doing
> / expecting at this point in time? I would have sworn that the long term
> part of EFI "distro boot" would be using bootmgr since that's the
> standards based way to set boot order. And if you don't have a device
> tree in U-Boot, and want the distribution one, aren't you then using
> something like grub which has a "dtb" keyword to handle that on its own?
> That's not saying that "distro boot" doesn't need to load the device
> tree, for when it's then calling booti/bootz/bootm, but not for the EFI
> case these days? Or no?

That's all fine, but the goal here is to match the functionality we
have today, i.e. the distroboot scripts. If people move to bootmgr for
EFI at some point, that's a separate thing from this patch. If I am
misunderstanding something, please let me know.

Regards,
SImon