Hi Tom,
On Mon, 17 Feb 2025 at 11:50, Tom Rini <tr...@konsulko.com> wrote:
>
> On Tue, Feb 11, 2025 at 03:22:22PM -0600, Tom Rini wrote:
> > On Tue, Feb 11, 2025 at 08:03:20AM -0700, Simon Glass wrote:
> > > Hi,
> > >
> > > I just wanted to send a note to (re-)introduce my ideas[1] for the
> > > next iteration of xPL.
> > >
> > > A recent series introduced 'xPL' as the name for the various
> > > pre-U-Boot phases, so now CONFIG_XPL_BUILD means that this is any xPL
> > > phase and CONFIG_SPL means this really is the SPL phase, not TPL. We
> > > still use filenames and function naming which uses 'spl', but could
> > > potentially adjust that.
> > >
> > > The major remaining problem IMO is that it is quite tricky and
> > > expensive (in terms of time) to add a new phase. We also have some
> > > medium-sized problems:
> > >
> > > a. The $(PHASE_), $(SPL_) rules in the Makefile are visually ugly and
> > > can be confusing, particularly when combined with ifdef and ifneq
> > >
> > > b. We have both CONFIG_IS_ENABLED() and IS_ENABLED() and they mean
> > > different things. For any given option, some code uses one and some
> > > the other, depending on what problems people have met along the way.
> > >
> > > c. An option like CONFIG_FOO is ambiguous, in that it could mean that
> > > the option is enabled in one or more xPL phases, or just in U-Boot
> > > proper. The only way to know is to look for $(PHASE_) etc. in the
> > > Makefiles and CONFIG_IS_ENABLED() in the code. This is very confusing
> > > and has not scaled well.
> > >
> > > d. We need to retain an important feature: options from different
> > > phases can depend on each other. As an example, we might want to
> > > enable MMC in SPL by default, if MMC is enabled in U-Boot proper. We
> > > may also want to share values between phases, such as TEXT_BASE. We
> > > can do this easily today, just by adding Kconfig rules.
> >
> > I agree with a through c and for d there are likely some cases even if
> > I'm not sure TEXT_BASE is a good example. But I'm not sure it's as
> > important as the other ones.
> >
> > > Proposal
> > >
> > > 1. Adjust kconf to generate separate autoconf.h files for each phase.
> > > These contain the values for each Kconfig option for that phase. For
> > > example CONFIG_TEXT_BASE in autoconf_spl.h is SPL's text base.
> > >
> > > 2. Add a file to resolve the ambiguity in (c) above, listing the
> > > Kconfig options which should not be enabled/valid in any xPL build.
> > > There are around 200 of these.
> > >
> > > 3. Introduce CONFIG_PPL as a new prefix, meaning U-Boot proper (only),
> > > useful in rare cases. This indicates that the option applies only to
> > > U-Boot proper and is not defined in any xPL build. It is analogous to
> > > CONFIG_TPL_xxx meaning 'enabled in TPL'. Only a dozen of these are
> > > needed at present, basically to allow access to the value for another
> > > phase, e.g. SPL wanting to find CONFIG_PPL_TEXT_BASE so that it knows
> > > the address to which U-Boot should be loaded.
> > >
> > > 4. There is no change to the existing defconfig files, or 'make
> > > menuconfig', which works just as today, including dependencies between
> > > options across all phases.
> > >
> > > 5. (next) Expand the Kconfig language[2] to support declaring phases
> > > (SPL, TPL, etc.) and remove the need for duplicating options (DM_MMC,
> > > SPL_DM_MMC, TPL_DM_MMC, VPL_DM_MMC), so allowing an option to be
> > > declared once for any/all phases. We can then drop the file in 2
> > > above.
> > >
> > > With this, maintaining Kconfig options, Makefiles and adding a new
> > > phase should be considerably easier.
> >
> > I think this will not make our life easier, it will make things harder.
> >
> > I think what we've reached now shows that Yamada-san was correct at the
> > time in saying that we were going down the wrong path with how we
> > handled SPL/TPL.
> >
> > My request instead is:
> > - Largely drop SPL/TPL/VPL (so no DM_MMC and SPL_DM_MMC and so on, just
> > DM_MMC) as a prefix.
> > - Likely need to introduce a PPL symbol as you suggest.
> > - Make PPL/SPL/TPL/VPL be a choice statement when building a defconfig.
> > - Split something like rockpro64-rk3399_defconfig in to
> > rockpro64-rk3399_ppl_defconfig
> > rockpro64-rk3399_spl_defconfig rockpro64-rk3399_tpl_defconfig
> > and add Makefile logic such that for X_defconfig as a build target but
> > not configs/X_defconfig not existing, we see if any of
> > configs/X_{ppl,spl,tpl,vpl}_defconfig exist and we run a builds in
> > subdirectories of our object directory, and then using binman combine
> > as needed.
> > - Maybe instead the Makefile logic above we would parse X_defconfig
> > and see if it's a different format of say PHASE:file to make it
> > easier to say share a single TPL config with all rk3399, have a few
> > common SPL configs and then just a board specific PPL.
> >
> > This solves (a) by removing them entirely. This solves (b) by removing
> > the ambiguity entirely (it will be enabled or not). As a bonus for (b)
> > we can switch everyone to IS_ENABLED(CONFIG_FOO) and match up with the
> > Linux Kernel again. This solves (c) again by removing it entirely.
>
> Lets come back up here, to my proposal, since parts of it seem to have
> not been clear enough. While what I'm proposing should work for any
> platform and xPL -> xPL -> ... -> PPL, for this example let us assume
> rockpro64-rk3399 supports the flow of TPL -> SPL -> PPL. Also, to
> compare with today, it will be helpful to run "make
> O=/tmp/rockpro64-rk3399_current rockpro64-rk3399_config" and have the
> resulting .config file available.
>
> There shall be configs/rockpro64-rk3399_tpl_defconfig. This will contain
> lines such as:
> CONFIG_ARM=y
> CONFIG_ARCH_ROCKCHIP=y
> CONFIG_ROCKCHIP_RK3399=y
> CONFIG_TPL=y
>
> When you run "make O=/tmp/rockpro64-rk3399_tpl rockpro64-rk3399_tpl_defconfig"
> the resulting .config file will contain lines such as:
> # CONFIG_ROCKCHIP_EXTERNAL_TPL is not set
> as this only makes sense in the context of building something that will
> be TPL.
>
> A more complex example is that it will also contain:
> CONFIG_TPL_ROCKCHIP_COMMON_BOARD=y
>
> Because looking at arch/arm/mach-rockchip/Makefile a bunch of that will
> be able to be simplified (and spl_common.c should be renamed to
> xpl_common.c) to:
> obj-$(CONFIG_SPL_ROCKCHIP_COMMON_BOARD) += spl.o spl-boot-order.o xpl_common.o
> obj-$(CONFIG_TPL_ROCKCHIP_COMMON_BOARD) += tpl.o xpl_common.o
>
> The .config file here will also contain:
> CONFIG_DM_SERIAL=y
>
> What it will not contain is:
> CONFIG_TPL_DM_SERIAL=y
>
> This is because there is no 'config TPL_DM_SERIAL' option in
> drivers/serial/Kconfig anymore.
>
> When you next run "make O=/tmp/rockpro64-rk3399_tpl all" the results in
> /tmp/rockpro64-rk3399_tpl would be similar to the results as under
> "/tmp/rockpro64-rk3399/tpl/" when building today.
>
> The contents of configs/rockpro64-rk3399_spl_defconfig would be similar
> to the tpl one, except with SPL-only-ever-valid options such as
> CONFIG_SPL_ROCKCHIP_COMMON_BOARD=y but otherwise have CONFIG_DM_SERIAL=y
> and no CONFIG_SPL_DM_SERIAL=y, and when building the "all" target, you
> would only get similar results to what is under the spl/ directory
> today.
>
> Next we have configs/rockpro64-rk3399_ppl_defconfig. When you run "make
> O=/tmp/rockpro64-rk3399_ppl rockpro64-rk3399_ppl_defconfig" the
> important difference is what you do not have. You do not have:
> CONFIG_SPL=y
> CONFIG_TPL=y
>
> Because we are not building SPL nor TPL. We're just making full U-Boot
> itself. This is where in more full examples and with additional
> restructure a "generic-arm64_ppl_defconfig" makes sense and be used
> instead.
>
> This brings up what to do with "ockpro64-rk3399_defconfig". And I'm a
> little unsure which of the things I mentioned above is best. It's
> either:
> a) Does not exist, top-level Makefile says roughly:
> %_defconfig: %_tpl_defconfig %_spl_defconfig %_ppl_defconfig
> make O=$(objdir)/tpl %_tpl_defconfig all
> make O=$(objdir)/spl %_spl_defconfig all
> make O=$(objdir)/ppl %_ppl_defconfig all
>
> But this might be too rigid.
> b) It contains:
> PHASE:VPL:rockpro64-rk3399_vpl_defconfig
> PHASE:TPL:rockpro64-rk3399_tpl_defconfig
> PHASE:SPL:rockpro64-rk3399_spl_defconfig
> PHASE:PPL:rockpro64-rk3399_ppl_defconfig
> And the top-level Makefile looks like:
> %_defconfig:
> grep -q ^PHASE $@ || fatal "Invalid defconfig file, please see..."
> foreach line in $@
> make O=$(objdir)/$PHASE $CONFIGFILE all
>
> It could also be some other suggestion.
Thanks for writing that up. It is somewhat clearer.
What happens to the Makefiles? Do they still have $(PHASE_) in them?
If so, what change is caused by having/not having it on any particular
line, with your proposed build system?
Regards,
Simon
