[PATCH v7 4/9] efi_loader: create default file boot option

[Ilias Apalodimas]

Hi all,

On Tue, 17 Oct 2023 at 08:33, Masahisa Kojima
<masahisa.kojima at linaro.org> wrote:
>
> Hi Heinrich,
>
> On Mon, 16 Oct 2023 at 23:52, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> >
> > On 16.10.23 15:00, Masahisa Kojima wrote:
> > > On Mon, 16 Oct 2023 at 21:46, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> > >>
> > >> On 16.10.23 14:31, Ilias Apalodimas wrote:
> > >>> Hi Heinrich,
> > >>>
> > >>> On Mon, 16 Oct 2023 at 10:06, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> > >>>>
> > >>>>
> > >>>>
> > >>>> Am 16. Oktober 2023 08:45:21 MESZ schrieb Masahisa Kojima <masahisa.kojima at linaro.org>:
> > >>>>> Current efibootmgr automatically creates the
> > >>>>> boot options of all disks and partitions installing
> > >>>>> EFI_SIMPLE_FILE_SYSTEM_PROTOCOL.
> > >>>>> Some of the automatically created boot options are
> > >>>>> useless if the disk and partition does not have
> > >>>>> the default file(e.g. EFI/BOOT/BOOTAA64.EFI).
> > >>>>>
> > >>>>> This commit only creates the boot option if the disk and
> > >>>>> partition have the default file so that system can directly
> > >>>>> boot from it.
> > >>>>
> > >>>> I don't directly see the user benefit.
> > >>>
> > >>> The user can add an HTTP boot option now and the installer will
> > >>> automatically start.  That would allow products to ship with a single
> > >>> boot option provisioned and run an installer on first boot
> > >>
> > >> This commit is not about HTTP. It changes how boot options for block
> > >> devices are created.
> > >>
> > >>>
> > >>>>
> > >>>> Reading all file systems will increase the boot time. Shouldn't we avoid this?
> > >>>
> > >>> Any idea what would be an alternative?  But when we added the
> > >>> automatic boot options we said we should avoid dynamic scanning and
> > >>> store results in a file.  This is doing a similar thing.  The only
> > >>> difference is that it mounts the iso image before adding the boot
> > >>> option.
> > >>
> > >> The alternative is to keep showing boot options for block devices even
> > >> if there is no BOOTxxxx.EFI file.
> > >>
> > >>>
> > >>>>
> > >>>> What does EDK II do?
> > >>>
> > >>> No Idea :)
> > >>
> > >>
> > >> On my workstation I get generated boot options
> > >>
> > >> Boot0001* UEFI:CD/DVD Drive     BBS(129,,0x0)
> > >> Boot0003* UEFI:Removable Device BBS(130,,0x0)
> > >> Boot0004* UEFI:Network Device   BBS(131,,0x0)
> > >>
> > >> without any media inserted and without any PXE server available.
> > >
> > > It is just information about how the EDK2 works.
> > > When I attach the Fedora installation media on EDK2(OVMF),
> > > the automatically generated boot option is as follows.
> > >
> > > UEFI QEMU HARDDISK QM00001 : PciRoot(0x0)/Pci(0x1,0x1)/Ata(Primary,Master,0x0)
> >
> > An ATAPI drive typically is not removable. So I wonder why it is listed.
> > Did you set the removable flag on the command line?
>
> I guess it is not removable(actually I don't know how to set the
> device as removable).
> I just attached the iso image to QEMU with something like '-hda
> Fedora_netinst.iso".
>
> According to the EDK II implementation[1], the boot option is
> enumerated with the following order.
>   1. Removable BlockIo
>   2. Fixed BlockIo
>   3. Non-BlockIo SimpleFileSystem
>   4. LoadFile
> So boot option for the fixed device such as HDD is also automatically created.
>
> [1] https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Library/UefiBootManagerLib/BmBoot.c#L2150
>
> >
> > >
> > > When this boot option is selected, Fedora installer automatically starts.
> > > So EDK II is searching the default file on the fly.
> >
> > What is shown if you attach a medium without Bootaa64.efi?
>
> The same boot option is created.
> UEFI QEMU HARDDISK QM00001 : PciRoot(0x0)/Pci(0x1,0x1)/Ata(Primary,Master,0x0)

I went back to reading the spec and I think Heinrich is right.  We
don't need that check at all. Going through [0] paragraph 4 says
" This search occurs when the device path of the boot image listed in
any boot option points directly to an EFI_SIMPLE_FILE_SYSTEM_PROTOCOL
device and does not specify the exact file to load"

So we should *only* add an automatic variable without the default
application.  Our code in try_load_entry() will search for that

[0] https://uefi.org/specs/UEFI/2.10/03_Boot_Manager.html#load-option-processing

Regards
/Ilias
>
> Thanks,
> Masahisa Kojima
>
> >