Passing boot logs to Linux?

[Heinrich Schuchardt]

On 12/20/23 05:11, Simon Glass wrote:
> +Heinrich Schuchardt
>
> On Tue, 19 Dec 2023 at 13:33, Daniel Golle <daniel at makrotopia.org> wrote:
>>
>> Hi Bence,
>>
>> On Tue, Dec 19, 2023 at 08:08:48PM +0000, Csókás Bence wrote:
>>> Hi!
>>>
>>> Is passing the U-Boot boot log to Linux supported yet? We are working
>>> with a third-party solution, which works, but is a bit hacky, so I was
>>> wondering if an official solution has been merged yet.

U-Boot supports writing log messages to an rsyslog server via broadcast
to UDP port 514 (CONFIG_LOG_SYSLOG=y).

The device name can be set via environment variable log_hostname.

If you have a log server for your devices in the same network segment,
you can consolidate all your logs there.

A driver writing log messages to a file could be created in U-Boot.

>>>
>>> I saw that there was an option CONFIG_CONSOLE_RECORD that saves
>>> everything to a membuff, but I don't know if that can be exported to
>>> Linux yet. And if not in the tree yet, would such a patch be welcome?

It is not enough to export a memory buffer. There must be support in the
operating system to read it.

Linux supports the common platform error record (CPER) format defined in
the UEFI specification. See

* https://www.dmtf.org/sites/default/files/PMCI_CPEREvent_Proposal_v3.pdf
*
https://uefi.org/sites/default/files/resources/Spike%20Yuan-%20Server%20RAS%20and%20UEFI%20CPER_final.pdf

Boot errors can be reported via the ACPI BERT table. But that won't help
you in OpenWRT which uses device-trees.

Best regards

Heinrich

>>
>> To me this sounds very useful and definitely something we'd like to
>> have in OpenWrt. So I'd volunteer to review and test your patches once
>> they are ready.
>>
>> What comes to mind is that CONFIG_CONSOLE_RECORD also captures ANSI
>> sequences during menu or count-down before boot, so we'd have to either
>> introduce a dedicated log_printf() call and use that when ever we want
>> the output to also become part of the log buffer or we could somehow
>> filter the recorded console, eliminating all terminal control sequences.
>
> I have been asking for this for a while. We need some sort of inline
> function to enable ANSI output. Perhaps something like this?
>
> #if CONFIG_IS_ENABLED(ANSI)
> bool use_ansi(void);
> #else
> static inline bool use_ansi(void) { return false; }
> #endif
>
> bool use_ansi(void)
> {
>      return gd->flags & GD_FLG_ANSI;
> }
>
>>
>>
>> Cheers
>>
>>
>> Daniel
>
> Regards,
> SImon