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

[Heinrich Schuchardt]

Am 3. April 2023 16:17:42 MESZ schrieb Tom Rini <trini at konsulko.com>:
>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.

Distroboot used to load the devicetree from a default location too.

This makes good sense on many boards but poses a problem for secure boot.

@Ilias, we need to evaluate this.

Regards

Heinrich

>
>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.
>