Fit images and EFI_LOAD_FILE2_PROTOCOL

[François Ozog]

Le sam. 3 oct. 2020 à 13:14, François Ozog <francois.ozog at linaro.org> a
écrit :

>
>
> Le sam. 3 oct. 2020 à 10:51, Heinrich Schuchardt <xypron.glpk at gmx.de> a
> écrit :
>
>> Hello Ilias, hello Christian,
>>
>>
>>
>> with commit ec80b4735a59 ("efi_loader: Implement FileLoad2 for initramfs
>>
>> loading") Ilias provided the possibility to specify a device path
>>
>> (CONFIG_EFI_INITRD_FILESPEC) from which an initial RAM disk can be
>>
>> served via the EFI_FILE_LOAD2_PROTOCOL.
>>
>>
>>
>> Ard extended the Linux EFI stub to allow loading the initial RAM disk
>>
>> via the EFI_FILE_LOAD2_PROTOCOL with the utmost priority.
>>
>>
>>
>> With commit ecc7fdaa9ef1 ("bootm: Add a bootm command for type
>>
>> IH_OS_EFI") Cristian enabled signed FIT images that contain a device
>>
>> tree and a UEFI binary (enabled by CONFIG_BOOTM_EFI=y).
>>
>>
>>
>> In the DTE calls we have discussed that it is unfortunate that we do not
>>
>> have a method to validate initial RAM images in the UEFI context.
>>
>>
>>
>> To me it would look like a good path forward to combine the two ideas:
>>
>>
>>
>> * Let the signed FIT image (of type IH_OS_EFI) contain a RAM disk
>>
>> * Pass location and size to the UEFI subsystem and serve them via
>>
>>   the EFI_FILE_LOAD2_PROTOCOL.
>>
>>
>>
>> We could also extend the bootefi command to be callable as
>>
>>
>>
>>    bootefi $kernel_addr_r $ramdisk_addr_r:$filesize $fdt_addr_r
>>
>>
>>
>> like the booti command to serve an initial RAM disk.
>>
>>
>>
>> What are your thoughts?
>
> that looks super interesting.
> I propose something (in the latest desk preparing oct 14th) similar except
> the an efi application boots the FIT.
> I view UEFI as booting a PE coff and pass a set of config tables. Today we
> have DTB, we could just add Initrd (you command line). Bootefi would be
> responsible to valide the containing FIT before pushing initrd (and
> dTB?)into the table. It would be the responsibility of the efi stub to get
> the initrd from the config table (GUID to be defined).
>
the memory attributes of the initrd config table should be such that it can
be recovered for normal use. That may be tricky though.

>
>
>>
>>
>>
>> Best regards
>>
>>
>>
>> Heinrich
>>
>> --
> François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group*
> T: +33.67221.6485
> francois.ozog at linaro.org | Skype: ffozog
>
>
>
> --
François-Frédéric Ozog | *Director Linaro Edge & Fog Computing Group*
T: +33.67221.6485
francois.ozog at linaro.org | Skype: ffozog