On Thu, Feb 13, 2025 at 05:50:13AM -0700, Simon Glass wrote:
> Hi Tom,
>
> On Wed, 12 Feb 2025 at 15:58, Tom Rini <tr...@konsulko.com> wrote:
> >
> > On Wed, Feb 12, 2025 at 01:05:11PM -0700, Simon Glass wrote:
> > > Hi Tom,
> > >
> > > On Wed, 12 Feb 2025 at 11:35, Tom Rini <tr...@konsulko.com> wrote:
> > > >
> > > > On Wed, Feb 12, 2025 at 10:41:45AM -0700, Simon Glass wrote:
> > > > > Hi Tom,
> > > > >
> > > > > On Wed, 12 Feb 2025 at 09:40, Tom Rini <tr...@konsulko.com> wrote:
> > > > > >
> > > > > > On Tue, Feb 11, 2025 at 03:54:21PM -0700, Simon Glass wrote:
> > > > > > > Hi Tom,
> > > > > > >
> > > > > > > On Tue, 11 Feb 2025 at 14:22, Tom Rini <tr...@konsulko.com> 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.
> > > > > > >
> > > > > > > OK. No, TEXT_BASE is not a great example in my book either. But
> > > > > > > it is
> > > > > > > true that SPL needs to know U-Boot's text base.
> > > > > > >
> > > > > > > Here's another:
> > > > > > >
> > > > > > > config SPL_SYS_MALLOC_F_LEN
> > > > > > > default SYS_MALLOC_F_LEN
> > > > > > >
> > > > > > > config TPL_SYS_MALLOC_F
> > > > > > > default y if SPL_SYS_MALLOC_F
> > > > > > >
> > > > > > > config TPL_SYS_MALLOC_F_LEN
> > > > > > > depends on TPL_SYS_MALLOC_F
> > > > > > > default SPL_SYS_MALLOC_F_LEN
> > > > > >
> > > > > > Alternatively:
> > > > > > config SYS_MALLOC_LEN
> > > > > > ... current default X if Y
> > > > > > default 0x2800 if RCAR_GEN3 && !PPL
> > > > > > default 0x2000 if IMX8MQ && !PPL
> > > > >
> > > > > PPL means (in my book) that we have a PPL, i.e. it is always true. It
> > > >
> > > > And in my proposal you're choosing between PPL, SPL, TPL, VPL.
> > > >
> > > > > is the same today, with SPL. We have CONFIG_SPL_BUILD which indicates
> > > > > which build it is. If you are suggesting that SPL means that this is
> > > > > the SPL build, then which thing tells us whether or not we have an SPL
> > > > > build? I'm just a bit confused by this.
> > > >
> > > > And we wouldn't have CONFIG_SPL_BUILD because we would either be
> > > > configuring for SPL=y or SPL=n, there's no confusion anymore.
> > > >
> > > > > But how can I make the TPL value of SYS_MALLOC_F_LEN the same as the
> > > > > SPL one, with your scheme?
> > > >
> > > > If your question is "how do I set an arbitrary but consistent value in
> > > > SPL and SPL" that's not enforced. But they also shouldn't be arbitrary
> > > > and we should have sane defaults set in Kconfig, regardless of either
> > > > proposal. While I'm trying to not get lost in the details today we have
> > > > 80 matches on "git grep SPL_.*_LEN= configs/" and 2 for TPL and I would
> > > > encourage someone to verify those are needed. My initial recollection is
> > > > that most of these are from when we bumped SYS_MALLOC_F_LEN or so up to
> > > > the commonly used default and had the few platforms that didn't use the
> > > > new default previously switch to the old one.
> > > >
> > > > In other words, I don't think there's a problem here that isn't solved
> > > > today, outside of either proposal.
> > > >
> > > > > So I'm still not understanding how you handle Kconfig dependencies
> > > > > between phases with your scheme. Are you saying you don't and they are
> > > > > not important?
> > > >
> > > > Basically. The majority of the cases of:
> > > > config SPL_FOO
> > > > default y if FOO
> > > >
> > > > config TPL_FOO
> > > > default y if SPL_FOO
> > > >
> > > > Just go away because FOO is already default y or select/imply'd by
> > > > TARGET_BAR or ARCH_BAZ.
> > > >
> > > > > Also, is there a single Kconfig tree for U-Boot, or are you saying you
> > > > > want a different set of Kconfig files for each phase?
> > > >
> > > > Just the Kconfig files we have today. Likely with less overall lines
> > > > since for example we could drop:
> > > > config SPL_FS_EXT4
> > > > bool "Support EXT filesystems"
> > > > select SPL_CRC16 if EXT4_WRITE
> > > >
> > > > Since we already have fs/ext4/Kconfig.
> > > >
> > > > > > > > > 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.
> > > > > > >
> > > > > > > You've mentioned this quite a few times over the years. Is there a
> > > > > > > reference to what he suggested we should do? Or perhaps it is
> > > > > > > what you
> > > > > > > have below.
> > > > > >
> > > > > > I don't recall what he proposed instead, just that when it became
> > > > > > clear
> > > > > > that I wanted to move from the "S:CONFIG_FOO.." syntax for how SPL
> > > > > > was
> > > > > > handled to how we're doing it today, he thought that was the wrong
> > > > > > direction.
> > > > >
> > > > > Yes, IMO he was right about that.
> > > > >
> > > > > >
> > > > > > > > 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.
> > > > > > >
> > > > > > > Good idea.
> > > > > > >
> > > > > > > > - 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.
> > > > > > >
> > > > > > > This means splitting the existing file into a separate one for
> > > > > > > each
> > > > > > > phase. I believe that will be hard to manage.
> > > > > >
> > > > > > Do you mean initially, or long term? Initially, it should be a bit
> > > > > > of
> > > > > > shell scripting. The consolidation (ie most/all rk3399 having an
> > > > > > identical _spl_defconfig) can't be automated. Long term I'm not
> > > > > > sure it
> > > > > > would be any different. Most of the maintenance is on resync'ing
> > > > > > which
> > > > > > is automated.
> > > > >
> > > > > Long term. How does 'make menuconfig' work in this case? Won't you
> > > > > have to run it three times for SPL, TPL and PPL?
> > > >
> > > > Yes, you would run configure for what you're building. This is a good
> > > > thing as it will no longer be so confusing to hunt down where SPL or TPL
> > > > or VPL options for a specific thing reside.
> > > >
> > > > > > > > - 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.
> > > > > > >
> > > > > > > The scheme I propose removes a-c also. I should have made that
> > > > > > > clear.
> > > > > >
> > > > > > Er, ok. That's not how it looked before, but I guess I'm just
> > > > > > mistaken.
> > > > >
> > > > > Yes I think so...it was a major goal to remove this stuff. [1] [2]
> > > >
> > > > Thanks.
> > > >
> > > > > > > There is not a huge difference between your scheme and mine. My
> > > > > > > question is, how do you handle (d)?
> > > > > >
> > > > > > Well, either (d) isn't important as for example MMC wasn't a good
> > > > > > choice
> > > > > > in your proposal as virtually everyone "select MMC" today or it's
> > > > > > handled more easily as my example above in SYS_MALLOC_LEN.
> > > > > >
> > > > > > > The way I see it, both schemes remove the ambiguity. Mine retains
> > > > > > > a
> > > > > > > single deconfig file and a single 'make menuconfig' for each
> > > > > > > board.
> > > > > > > Yours feels more like building independent U-Boot images.
> > > > > >
> > > > > > It is explicitly building independent U-Boot images, yes. With a
> > > > > > wrapper
> > > > > > around "make all of the images for a given platform". So much of our
> > > > > > confusing and messy code is because we aren't doing that. And since
> > > > > > most
> > > > > > modern SoCs can work as (mostly )generic SPL selects correct DTB
> > > > > > for PPL
> > > > > > we really could have fewer overall build configurations.
> > > > >
> > > > > I'd really like to see a generic aarch64 U-Boot for PPL, although it
> > > > > would be quite large with all the drivers. Perhaps we could start by
> > > > > having a generic Rockchip one, for example.
> > > > >
> > > > > Still I don't see this being strongly related to the discussion about
> > > > > these two different schemes.
> > > >
> > > > Well, in your scheme how do we have say generic-aarch64_defconfig
> > > > function on either chromebook_bob or am62x_beagleplay_a53 ? In mine,
> > > > since everything is a separate build, generic-aarch64_defconfig has
> > > > PPL=y, ARCH_K3=y and ROCKCHIP_RK3399=y. And then
> > > > chromebook_bob_defconfig would say to use chromebook_bob_tpl_defconfig,
> > > > generic-rk3399_spl_defconfig and generic-aarch64_defconfig. As a bonus
> > > > instead of am62x_beagleplay_a53_defconfig and
> > > > am62x_beagleplay_r5_defconfig we would have am62x_beagleplay_defconfig
> > > > that would say to use the appropriate SPL/PPL for R5, and appropriate
> > > > SPL/PPL for A53.
> > > >
> > > > But the one big huge caveat I want to make here is that "generic" images
> > > > are useful in some use cases (I'm sure all of the regular F/OSS
> > > > distributions would love a single actually common PPL if they can fit
> > > > it) will strip things down. Whatever the IoT edge device closest to you
> > > > now really won't want to ship with all the platforms enabled. Image size
> > > > still matters.
> > >
> > > OK thanks for the details. I think I have a reasonable idea of what
> > > you are proposing, now. It would work, but is quite radical, IMO.
> > > That's not necessarily a bad thing, but in my mind I see a sequencing
> > > possibility.
> > >
> > > A few points from my side:
> > >
> > > 1. I would love to see the defconfig files reduce in size, with more
> > > and better defaults. One way to do this would be to enforce a maximum
> > > length. I added a feature to qconfig to allow finding common options
> > > among boards (the -i flag), but I'm not sure if many people use it.
> >
> > I don't see reducing defconfig size as important honestly. Should we
> > have more and better defaults? Yes. But almost everything is under 200
> > lines with the biggest (non-sandbox) ones being the generic zynqmp
> > platform(s?).
>
> Agreed.
>
> >
> > > 2. Generic boards is something I have been pushing for years (in fact
> > > it is why I originally introduced devicetree), but I'm not seeing a
> > > lot of traction.
> >
> > I don't think generic boards are universally helpful. Even if what I'm
> > proposing would allow for more of it, below the PPL stage I'm not sure
> > it's both feasible enough and useful enough for production. At the PPL
> > stage it still has to be small enough and not overly burdensome. What we
> > talked about on the call yesterday about using more multi-dtb images is
> > a step in the right direction, yes.
>
> Agreed. Anway, we can create separate targets for generic boards if we want
> to.
>
> >
> > > 3. Iit seems that you want to remove all the 'if SPL' pieces and just
> > > rely on the current PPL configuration. But how will that work? There
> > > are tons of features which don't work in SPL, or are not relevant, or
> > > have special 'small' versions. That is a *lot* of Kconfig refactoring
> > > just to get something working, isn't it? With my scheme there is no
> > > Kconfig change needed initially - it can be done later as needed /
> > > desirable.
> >
> > I don't think we would remove most "if SPL" cases. Taking part of the
> > current stanza for ROCKCHIP_RK3399 as an example:
> > config ROCKCHIP_RK3399
> > bool "Support Rockchip RK3399"
> > select ARM64
> > select SUPPORT_SPL
> > select SUPPORT_TPL
> > select SPL
> > select SPL_ATF
> > select SPL_BOARD_INIT if SPL
> > ...
> > select SPL_CLK if SPL
> > ...
> > select CLK
> > ...
> > imply TPL_CLK
> >
> >
> > This would become:
> > config ROCKCHIP_RK3399
> > bool "Support Rockchip RK3399"
> > select ARM64
> > select SUPPORT_SPL
> > select SUPPORT_TPL
> > select SPL_ATF if SPL # TBD: Does 'ATF' make sense outside of SPL?
> > select BOARD_INIT if SPL # Not TPL_BOARD_INIT here
> > select CLK # imply was likely wrong before? Would need to check
> > ...
>
> I was more talking about the large blocks of 'if SPL' - e.g. we have
> common/spl/Kconfig and common/spl/Kconfig.tplI would vastly reduce the contents within those 'if' blocks, but there are still options that are xPL-centric without a PPL counterpart, such as SPL_ATF (I suspect, but if not I'm sure others). > But just the level of thought required in your small example above > suggests it is a large effort. Yes, restructuring our Kconfig logic and then removing our xPL logic is some work. So was, I suspect, all of what you did already. > > > 4. My scheme splits the config into separate files. Yours makes the > > > > I don't see yours as splitting the configs in to separate files, I see > > it as generating some intermediate objects. The configs don't change and > > that's one of our problem areas. > > So you mean a big problem area is the current Kconfig? I mean it's a problem for users a board developers to make valid configurations and update them as needed. Filesystems are in the filesystem menu, unless they're SPL and then it's all under the big SPL menu. > Mind generates > out to an include/generated/autoconf_xxx for each phase. Yes they are > intermediate files and auto-generated, but each 100% controls its > phase, so there is no confusion and CONFIG_IS_ENABLED() / odd Makefile > rules anymore. Yes, removing CONFIG_IS_ENABLED and $(PHASE_)/$(XPL_) from Makefiles is good. But the intermediate files aren't going to help (nor hurt) any of the problems themselves. If you're reading those to figure out a problem, it's like when you're reading a .i file to figure out a problem, it means you're already in a complex troublesome spot. But I don't know that CONFIG_SPL_FS_FAT=y means that CONFIG_FS_FAT=y for SPL builds leads to "no confusion". But I do think that CONFIG_SPL=y and CONFIG_FS_FAT=y does. > > > split earlier, at the Kconfig level. So it seems that we could go with > > > my scheme to get us to a split config, then, after that, decide > > > whether to move that split earlier to Kconfig itself. The choices > > > > I don't think so. Yours makes things complicated by making the build do > > even more (and from the RFC, the implementation tooling diverges from > > upstream). > > Yes it makes the kconf tool generate those separate files for each phase [3] > > > Mine makes things differently complicated by doing less for > > most things, but needing some thought on how to know that say > > chromebook_bob needs chromebook_bob_tpl_defconfig, > > chromebook_bob_spl_defconfig and chromebook_bob_ppl_defconfig to be > > built, before asking binman to go put things together. > > Yours seems feasible in a fully Binman world, but given the difficulty > we (or I) have completing a migration, I honestly don't believe this > is feasible in today's U-Boot. The other problem is that it all has to I'm not 100% sure it's everything needs binman actually. Or even if we do take this as a reason to push for more binman, it's just some trivial types already handled in the Makefile that's missing. > be done at once. We need to rewrite the Kconfig and flip over the > board. Will we carry people with us? That is a huge risk to the > project IMO. I'm not sure, actually, that it couldn't be done in stages. We might need a little bit of fakery around being able to just build SPL without PPL in the interim. > Anyway, yes my schema makes the build do even more (with 400 lines of > kconf additions and a patch that can likely be upstreamed). But > otherwise, it is a one-off improvement, without any changes to the > existing Kconfig. I thought Yamada-san rejected changes going in this direction before? But either way, no it's not likely the final overburden in terms of divergence. > So my point is that we could go with the first part of my scheme to > resolve the 'medium' problems then decide which way to continue after > that. From your side you won't have lost anything towards where you > want to head. The two options would then be: > > - exhance kconfig language to build in the notion of phases > - split the defconfigs for each board, redo the Kconfig rules and > teach the build to combine images If things go down your proposed path instead, no, I don't see that as making it meaningfully easier to go the way I proposed later. The only commonality is dropping $(PHASE_)/$(XPL_)/etc and CONFIG_IS_ENABLED -> IS_ENABLED. And (almost) all of that is a script'able change. > > > would then be to use your scheme (Kconfig refactoring, splitting > > > defconfigs and some rework), or to do my scheme (which would require > > > enhancing the Kconfig language a bit just for U-Boot and some optional > > > rework over time). Both schemes would need a small amount of > > > build-logic changes, but I'm not sure yet what that would look like. > > > > > > Does that sound right? > > > > With what I said above, yes I think we're closer at least to > > understanding each other. > > Yes. Well, with that, what now? What makes the current situation untenable is VPL. And I gather I haven't convinced you to put that on hold long enough to instead rework how we build things, have I? -- Tom
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