Re: [PATCH 0/8] efi_loader: Complete the bootflow_efi() test

[Tom Rini <trini@konsulko.com>]

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On Wed, Jan 08, 2025 at 10:02:52AM -0700, Simon Glass wrote:
> Hi Heinrich, Tom,
> 
> On Tue, 7 Jan 2025 at 08:47, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
> >
> > On 07.01.25 16:11, Tom Rini wrote:
> > > On Tue, Jan 07, 2025 at 06:57:50AM -0700, Simon Glass wrote:
> > >> Hi Heinrich,
> > >>
> > >> On Tue, 7 Jan 2025 at 06:11, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
> > >>>
> > >>> On 07.01.25 13:15, Simon Glass wrote:
> > >>>> Hi Heinrich,
> > >>>>
> > >>>> On Mon, 6 Jan 2025 at 10:00, Heinrich Schuchardt <xypron.glpk@gmx.de> wrote:
> > >>>>>
> > >>>>> On 06.01.25 15:47, Simon Glass wrote:
> > >>>>>> This test was hamstrung in code review so this series is an attempt to
> > >>>>>> complete the intended functionality:
> > >>>>>>
> > >>>>>> - Check memory allocations look correct
> > >>>>>> - Check that exit-boot-services removes active-DMA devices
> > >>>>>> - Check that the bootflow is still present after testapp finishes
> > >>>>>>
> > >>>>>> The EFI functionality duplicates bootm_announce_and_cleanup() and still
> > >>>>>> uses the defunct board_quiesce_devices() so a nice cleanup would be to
> > >>>>>> call the bootm function instead, with suitable modifications. That would
> > >>>>>> allow bootstage to work too.
> > >>>>>>
> > >>>>>> This series is based on sjg/master since the EFI logging was rejected so
> > >>>>>> far.
> > >>>>>
> > >>>>> Yes, it was rejected because a solution at the lib/log.c level would be
> > >>>>> more generic.
> > >>>>
> > >>>> As I mentioned, that idea isn't suitable for programmatic use.
> > >>>
> > >>> What can be done with show_addr("mem", rec->memory); that log_debug()
> > >>> does not offer or which you could not do with a new log function in
> > >>> lib/log.c that takes variadic arguments?
> > >>
> > >> There are asserts in [1], for example. How do you propose to handle
> > >> that? See [2] for my previous explanation, quoted here:
> > >>
> > >>> CONFIG_LOG with a bloblist option would be a great idea, but it's hard
> > >>> to programmatically scan text...plus only the external call sites are
> > >>> actually logged.
> > >>
> > >> Also see the discussion on the original patch [3]. There was also your
> > >> reply at [4], but I think you missed that this is intended for use in
> > >> unit tests (i.e. with ut_assert()).
> > >>
> > >> You also requested that this be generalised, rather than being
> > >> EFI-loader-specific. I have no objection to that, but don't have a use
> > >> case for it yet, so have deferred that to later. It's a fairly simple
> > >> change, if/when needed. If the series was not NAKed, I'd be happy to
> > >> do it now.
> > >>
> > >>>>
> > >>>>>
> > >>>>> Tom suggested not to send patches that are for private enjoyment to the
> > >>>>> mailing list.
> > >>>>
> > >>>> My contributions to U-Boot are only ever about private enjoyment :-)
> > >>>>
> > >>>> Do you have any comments on the patches?
> > >>
> > >> Regards,
> > >> Simon
> > >>
> > >> [1] https://patchwork.ozlabs.org/project/uboot/patch/20250106144755.3054780-6-sjg@chromium.org/
> > >> [2] https://lore.kernel.org/u-boot/CAFLszTjxOE_037+kR0jgdax80sBombYo_k0YgiuVnP=KZCOvuA@mail.gmail.com/
> > >> [3] https://lore.kernel.org/u-boot/CAC_iWjKtaN54B98OKbkoXkC_GmKJ=x+M4=UY_O6roSOpZaDxag@mail.gmail.com/
> > >> [4] https://lore.kernel.org/u-boot/D513D326-41A6-425E-B11F-85958065BCD2@gmx.de/
> > >
> > > Looking at the logging portions of the original series again, especially
> > > if this was made generic, we probably don't want to print to actual
> > > console every time we're making a note of some memory allocation for
> > > example, that would be unreadable outside of a debug context. The point
> > > of this really seems to be "log things for verifying in tests later".
> > > Does that end up being useful? I don't know. Heinrich or Ilias, do the
> > > tests in [1] look generally useful?
> > >
> >
> > The tests in [1] are not documented, not even in the commit message. So
> > the reasoning behind the tests remains Simon's secret.
> 
> Are you asking for code comments in the test? If so, I can add some.
> 
> >
> > At first sight the tests in [1] don't make much sense. E.g. that only a
> > subset of memory types have been used does not tell that the right
> > memory type has been used for the right object.
> 
> It is a pretty good start, though. It makes sure that the memory types
> are sane, checks addresses are within DRAM, etc. With [5] it makes
> sure that devices are removed.
> 
> >
> > Implementing a specific tracing functionality for EFI is definitively
> > the wrong way forward as it will lead to code duplication.
> 
> We can cross that bridge when we come to it.

Well, no. It's backwards to make a bridge in one place when everyone
agrees it needs to be moved somewhere else. I mean [5] is a generic
issue and test/py/tests/test_net_boot.py or some other test we already
have which tests booting an OS should confirm that we've quiesced
devices before moving on. And as a bonus it's in python where dealing
with strings doesn't suck.

> 
> >
> > We already have function _log() which is variadic.
> >
> > Simon could write a new log driver that parses the `format` parameter
> > and saves the binary data in an appropriate format for analysis by the
> > unit tests:
> >
> > * For %s the driver should save the string and not the address of the
> > string.
> > * For %pD the driver should save the device path instead of the pointer.
> > * ...
> >
> > Some changes to the log driver interface will be needed to pass the
> > variadic arguments instead of the formatted message.
> 
> Perhaps the word 'log' is confusing people. But the above suggestion
> is quite a complicated way of handling things. We have no way to
> decode printf() strings in this way. See log_dispatch() for how this
> is handled today. It uses sprintf(). Trying to test based on text
> output would be very clumsy (lots of regexes and sscan() calls?) and
> result in a huge amount of parsing code, highly dependent on the
> printf() format, etc.
> 
> I very-much doubt that would produce a useful implementation, but if
> you would like to try it out then I would be happy to look at it.
> 
> I mentioned this several times, but even if we did go that way, we
> only have logging on the external calls, so much of the EFI-memory
> allocation in U-Boot would not be logged.
> 
> Regards,
> Simon
> 
> [5] https://patchwork.ozlabs.org/project/uboot/patch/20250106144755.3054780-9-sjg@chromium.org/

Yes, calling this a "log" when it's intended for capturing information
for tests got some of this off on the wrong track. But that also helps
explain now that this is still on the wrong track and should instead be
following normal design practices for testing and expanding existing
infrastructure and not inventing a new everything. So if you don't like
Heinrich's suggestion, take a look at Caleb's suggestion. And if you
don't like Caleb's suggestion, go put this in a topic branch you can
merge when you need to debug some problem that seemingly nothing else
will catch.

-- 
Tom

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