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

Caleb Connolly
2025-01-08T13:39:11Z

On 07/01/2025 16:47, Heinrich Schuchardt 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.
>
> 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.
>
> Implementing a specific tracing functionality for EFI is definitively
> the wrong way forward as it will lead to code duplication.
>
> 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:

Isn't this precisely what monkeypatching is for in unit tests? imho this
does not make sense as a logging API but expanding FTRACE to have more
capabilities (like Linux trace has) so that it can save arguments and
then having some nice interface to assert that certain functions were
called in a certain order with certain arguments would be a scalable way
to go (and surely useful in other cases too).

Honestly though it seems quite wrong for the bootflow test to inspect
EFI memory allocations, these are completely different levels of API and
any tests like this are going to be prone to breaking over time just
because they're making assumptions across so many layers.

Kind regards,
>
> * 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.
>
> Best regards
>
> Heinrich

--
// Caleb (they/them)