[Buildroot] [PATCH 2/2] boot/systemd-boot: new package

Tue Dec 25 21:26:47 UTC 2018

On Tue, Dec 25, 2018 at 6:48 AM Yann E. MORIN <yann.morin.1998 at free.fr> wrote:
>
> James, All,
>
> On 2018-12-24 16:44 -0600, James Hilliard spake thusly:
> > On Mon, Dec 24, 2018 at 3:26 PM Yann E. MORIN <yann.morin.1998 at free.fr> wrote:
> > > On 2018-12-19 07:41 +0800, james.hilliard1 at gmail.com spake thusly:
> > > > From: James Hilliard <james.hilliard1 at gmail.com>
> [--SNIP--]
> > > > +     select BR2_PACKAGE_SYSTEMD_BOOT if BR2_INIT_SYSTEMD
> > > I think it is much more simple if you just do:
> > >     depends on !BR2_PACKAGE_SYSTEMD
> [--SNIP--]
> > > That way, you don't have to need to be schizophrenic about being a
> > > generic-package or a meson-package. Just be a meson-package.
> > So I ended up doing things this way so that the systemd-boot package
> > is used for the image installation regardless of where the bootloader
> > is compiled.
>
> Well, I don;t think that is interesting, becasue the duplication is not
> so big. There are in fact just a very few commands to do.
>
> Besides, with the way you split the patches, if only the first one is
> applied, then the boot files are in fact not installed. So that is not
> good. You need to ensure that the series is functional (and makes sense)
> even if only partially applied.
It is actually functional but only when used in a somewhat non-standard
way, if you don't do the images install step you still have the bootloader
installed to the target rootfs where it is useful for runtime installs. This
is a somewhat exotic use case, I do use use runtime installs myself
but I use systemd-boot for both the image and the runtime install so
I don't need this flexibility myself although I could see others
potentially needing it. One potential use case for this would be if
someone needs to create a runtime installer that will dynamically
choose to install grub or systemd-boot depending on the target system
configuration but needs to build the image(for say a USB jump drive) which
uses grub for booting itself but installs systemd-boot to the internal
hard disk.
>
> > > > +     select BR2_PACKAGE_UTIL_LINUX
> > > > +     select BR2_PACKAGE_UTIL_LINUX_LIBBLKID
> > >
> > > Beware, that libblkid uses fork(), so needs an MMU, so you need to
> > > propagate that dependency with (the comment is to indicate that it's an
> > > inherited dependency):
> > >
> > >     depends on BR2_USE_MMU # util-linux' libblkid
> > >
> > > But since we're only building the boot blobs, can we do away without
> > > util-linux?
> > The issue I was running into here is that systemd's meson build system
> > will not work without util-linux, even though util-linux does not need
> > to be installed for the bootloader to function.
>
> I made a very small patch to no longer require that, but it is
> definietely not upstreamable. See below...
>
> > > Looking at an impothetical situation (e.g. recovery system, or a
> > > first-stage initramfs...):
> > >
> > >     minimalist system with just busybox,
> > >   - systemd-boot as bootloader
> > >
> > > this would force having util-linux library, even though nothing would
> > > use them...
> > Yeah, this isn't ideal, from my discussions with systemd upstream
> > there would need to be a major refactoring of their meson build system
> > to allow building systemd-boot without util-linux.
>
> OK, I found your PR: https://github.com/systemd/systemd/pull/11141
> Next time you say "I talked with upstream", please add a pointer, so we
> can go and see the discussion without asking you to explain all of it
> again. ;-)
>
> > Is there a way to
> > satisfy the util-linux requirement without actually installing
> > util-linux into the target?
>
> Needs a patch, see below...
>
> > > > diff --git a/boot/systemd-boot/buildroot.conf b/boot/systemd-boot/buildroot.conf
> > > > diff --git a/boot/systemd-boot/loader.conf b/boot/systemd-boot/loader.conf
> > > I see that your previous patch in systemd did not provide thoose two
> > > files.
> > I think I just had them in a different place, I'm not actually sure
> > how useful it is to provide this since most setups will need to
> > customize them in their post-image.sh. I included them since other
> > packages like grub and gummiboot also provide defaults.
>
> As I said previously, I don't think it is a good idea. And as explained
> above, that means your series is not working is only the first patch is
> applied.
>
> [--SNIP--]
> > > > +SYSTEMD_BOOT_SITE = $(call github,systemd,systemd,v$(SYSTEMD_BOOT_VERSION))
> > > > +SYSTEMD_BOOT_DL_SUBDIR = systemd
> > > Yes! :-)
>
> In fact, it does not work as expected, because the generated tarball is
> named ''systemd-boot-239.tar.gz instead of 'systemd-239.tar.gz'.
>
> But it can be made to work by adding an explicit:
>
>     SYSTEMD_BOOT_SOURCE = systemd-$(SYSTEMD_BOOT_VERSION).tar.gz
>
> [--SNIP--]
> > > > +ifeq ($(BR2_PACKAGE_SYSTEMD_BOOT),y)
> > > > +define SYSTEMD_BOOT_BUILD_CMDS
> > > > +     mkdir -p $(@D)/build/src/boot/efi
> > > > +     cp $(TARGET_DIR)/usr/lib/systemd/boot/efi/systemd-boot$(SYSTEMD_BOOT_IMGARCH).efi \
> > > > +             $(@D)/build/src/boot/efi/systemd-boot$(SYSTEMD_BOOT_IMGARCH).efi
> > > > +     cp $(TARGET_DIR)/usr/lib/systemd/boot/efi/linux$(SYSTEMD_BOOT_IMGARCH).efi.stub \
> > > > +             $(@D)/build/src/boot/efi/linux$(SYSTEMD_BOOT_IMGARCH).efi.stub
> > > > +endef
> > >
> > > You can now also get rid of this trick.
> > So I have things like this so that the bootloader built by the systemd
> > package can be reused by the systemd-boot package.
>
> Yeah, I understand why you did that (but you should have said so in the
> commit log), and I still do not think it is worth the complexity.
>
> Yet, to prove how much more simple it is if you just accept the little
> duplication, and because I did not have anything better to do during
> x-mas, please have a look at the series I prepared, last three commits
> on:
>     https://git.buildroot.org/~ymorin/git/buildroot/log?h=yem/systemd-boot
>
> I tested building systemd-boot standalone, and it works (not sure it
> boots, I did not run-test it). I however did not try to test-build the
> config where it is provided by systemd itself; I'll let it to you as an
> exercise. ;-)
>
> Feel free to grab those commits and ammend them further if needed; if
> not, just grab them and resend them (you can git-fetch from
> git://git.buildroot.org/~ymorin/git/buildroot).
Will do, I agree your approach is simpler and easier to understand.
>
> However, if you do add new features (TPM, more archs), please do so as
> additional patches, so the whole series is easier to review.
I'll follow up on that after initial systemd-boot support is merged.
>
> Regards,
> Yann E. MORIN.
>
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