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

Simon Glass
2025-01-08T17:03:13Z

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.

>
> 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/