Re: [PATCH v2 7/9] Make EFI_LOADER depend on DM and OF_CONTROL

[Tom Rini <trini@konsulko.com>]

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On Wed, Jul 28, 2021 at 07:44:37PM -0600, Simon Glass wrote:
> Hi,
> 
> On Wed, 28 Jul 2021 at 17:55, Tom Rini <trini@konsulko.com> wrote:
> >
> > On Thu, Jul 29, 2021 at 01:45:49AM +0200, Heinrich Schuchardt wrote:
> > >
> > >
> > > On 7/27/21 12:07 AM, Tom Rini wrote:
> > > > On Fri, Jul 02, 2021 at 12:36:18PM -0600, Simon Glass wrote:
> > > >
> > > > > This feature should never have been made available when driver model
> > > > > or devicetree are disabled. Add these as conditions, so that we don't
> > > > > create even more barriers to migration.
> > > > >
> > > > > Add a note about the substantial size increment associated with this
> > > > > option.
> > > > >
> > > > > Signed-off-by: Simon Glass <sjg@chromium.org>
> > > > > ---
> > > > >
> > > > > Changes in v2:
> > > > > - Split out new patch to make EFI_LOADER depend on DM and OF_CONTROL
> > > > > - Note the approximate size of this feature in the help
> > > > >
> > > > >   lib/efi_loader/Kconfig | 4 +++-
> > > > >   1 file changed, 3 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> > > > > index 6242caceb7f..466abfed300 100644
> > > > > --- a/lib/efi_loader/Kconfig
> > > > > +++ b/lib/efi_loader/Kconfig
> > > > > @@ -1,6 +1,6 @@
> > > > >   config EFI_LOADER
> > > > >           bool "Support running UEFI applications"
> > > > > - depends on OF_LIBFDT && ( \
> > > > > + depends on OF_LIBFDT && DM && OF_CONTROL && ( \
> > >
> > > Didn't Tom eliminate all boards without CONFIG_DM? Shouldn't we get rid
> > > of this symbol?
> >
> > No, but I did send out a message about that today as we're very close.
> > Much closer than I had expected us to be.
> 
> Note we will still have SPL_DM, I think.

Right.

> > > Are there boards using DM and not OF_CONTROL or OF_CONTROL and not DM?
> >
> > Yes, a few.  It's vexpress_aemv8a_semi, warp (fixed by
> > https://patchwork.ozlabs.org/project/uboot/patch/20210402180552.1075997-2-pbrobinson@gmail.com/
> > so false positive), cm_t335, devkit8000, armadillo-800eva, kzm9g and sniper.
> >
> > > Why are these separate symbols? Isn't this symbol to be eliminated, too?
> >
> > Simon?
> 
> If we do eliminate DM it will be in a separate series. Like Tom I am
> pleasantly surprised at how close we are.
> 
> But please let's consider patches on their merits. It is fine to reply
> with a wishlist but even better to reply with a follow-up patch.

OK.  So, build-wise, EFI_LOADER does not require OF_CONTROL.

> Somewhat related, I think we need to create a separate symbol which
> means (OF_CONTROL && !OF_PLATDATA) so we can just check one thing.
> 
> Also I think we should push of-platdata, since otherwise we're going
> to hit the same problem of migrating SPL boards to DM one day.

Note that we don't have CONFIG_OF_PLATDATA just
CONFIG_(SPL|TPL)_OF_PLATDATA.

> > > lib/efi_loader/efi_disk.c is the only place where we maintain duplicate
> > > code for DM and non-DM. A dependency on CONFIG_BLK (which itself depends
> > > on CONFIG_DM) would make more sense to me. But only in a patch
> > > eliminating the non-BLK code.
> >
> > I just know that off-hand, partition + disk + block has some corner
> > case, but maybe that corner case is unintentional in terms of usage
> > today.
> >
> > > > >                   ARM && (SYS_CPU = arm1136 || \
> > > > >                           SYS_CPU = arm1176 || \
> > > > >                           SYS_CPU = armv7   || \
> > > > > @@ -25,6 +25,8 @@ config EFI_LOADER
> > > > >             will expose the UEFI API to a loaded application, enabling it to
> > > > >             reuse U-Boot's device drivers.
> > > > >
> > > > > +   For ARM 32-bit, this adds about 90KB to the size of U-Boot.
> > > > > +
> > >
> > > There is no unit ISO prefix K. Do you mean KiB?
> > >
> > > 90 KiB may be the value today. Will you update it regularly? Otherwise
> > > don't put a number here.
> > >
> > > I can't see that the effect on size is truly architecture specific. Why
> > > do you refer to 32bit ARM?
> > >
> > > Such a comment would better fit into a documentation chapter on
> > > downsizing U-Boot.
> >
> > Yes, we should probably drop that specific note.
> 
> From my POV I really like these notes in Kconfig. They appear in a few
> places and provide people with rough guidance. I'd like to see more of
> them. I don't know how we can keep them up-to-date, although I'd argue
> that they should stay constant, if we are holding to our no-bloat
> ideal.

I feel like EFI gets a bit of an undeserved reputation here.  It's not
growing any worse than the rest of the world is over fixes and error
correction (which is to say, 16/32/40 bytes here and there).  And
there's not "big" new default features coming in.

-- 
Tom

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