Re: [RFC] Interface for installing bootloaders

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2018-09-04 11:27, Claudius Heine wrote:
> Hi Jan,
> 
> On 2018-09-04 09:17, [ext] Jan Kiszka wrote:
>> Hi all,
>>
>> for installing a bootloader into an image, a number of packages have 
>> to be installed into the buildchroot. These can be prebuilt packages 
>> or packages we build via Isar. Currently, we only handle the case of 
>> WIC requiring prebuilt Debian packages, and that in a hacky way (no 
>> proper distro abstraction, unneeded installation of unused 
>> dependencies). This proposal aims at providing a more holistic solution:
>>
>> - Introduce new variables that express the two types of dependencies:
>>     - BOOTLOADER_PREBUILT
>>     - BOOTLOADER_CUSTOM
>>
>>    So there is no "WIC" in these, any imaging recipe can use them.
>>
>> - Imaging recipes (e.g. via classes/wic-img.bbclass) should
>>     - install all packages from BOOTLOADER_PREBUILT and BOOTLOADER_CUSTOM
>>       into the buildchroot
>>     - DEPEND on all recipes in BOOTLOADER_CUSTOM
>>
>> - Define some common dependencies in conf/distro/${DISTRO}.conf:
>>     - GRUB_PREBUILT
>>     - GRUB_PREBUILT_append_${DISTRO_ARCH}
>>     - SYSLINUX_PREBUILT
>>     - ...
>>
>>    Those variables can then be used to initialize BOOTLOADER_PREBUILT as
>>    needed and also replace those nasty BUILDCHROOT_PREINSTALL_WIC in
>>    buildchroot-target.bb.
>>
>> - Set BOOTLOADER_PREBUILT or BOOTLOADER_CUSTOM in the
>>    conf/machine/${MACHINE}.conf or some overriding conf file - basically
>>    the same one that selects IMAGE_TYPE and WKS_FILE.
>>
>> Anything I missed? Better suggestions? Eventually, when we can derive 
>> bitbake recipe dependencies automatically from package dependencies, 
>> PREBUILT and CUSTOM could be folded together. Right now, we need that 
>> split.
>>
>> Jan
> 
> I have a class that I use for the current project that allows installing 
> additional packages into the buildchroot from within the image. I didn't 
> had time to prepare patches for it for mainline isar. But maybe that 
> goes into to right direction.
> 
> I attached it.

Yeah, can serve as pattern. I'd just like to abstract away from the user 
that fact the bootloader deps go into buildchroot, i.e. the user 
interface shall not be BUILDCHROOT_EXTRA_INSTALL / BUILDCHROOT_BUILD_DEP 
in the context of bootloader installation.

Jan