[U-Boot] [PATCH 0/4] Accurate boot time measurement

[Graeme Russ]

On 15/05/11 03:32, Simon Glass wrote:
> On Sat, May 14, 2011 at 4:34 AM, Mike Frysinger <vapier at gentoo.org> wrote:
> 
>> On Friday, May 13, 2011 16:51:59 Simon Glass wrote:
>>> This defines the basics of a new boot time measurement feature. This
>> allows
>>> logging of very accurate time measurements as the boot proceeds, by using
>>> an available microsecond counter.
>>>
>>> To enable the feature, define CONFIG_BOOTSTAGE in your board config file.
>>> Also available is CONFIG_BOOTSTAGE_REPORT which will cause a report to be
>>> printed just before handing off to the OS.
>>
>> this seems to overlap the existing show_boot_progress() code.  any chance
>> we
>> can look at these being merged ?
>> -mike
>>
> 
> Hi Mike,
> 
> Yes I did look at this a few weeks ago. It would be a pretty invasive
> change. That code just uses a whole lot of numbers which presumably are
> approximately how far through the boot process we are. Bootstage is intended
> as a debugging tool for performance tune-up rather than a user display tool.
> I could imagine adding a table to bootstage with the progess number for each
> bootstage id, but then people are going to complain that the bootstage
> report is far to long and includes uninteresting things. I suppose I could
> fix that by including a flag as to whether to report each item or not...but
> it any case as you can see it is not a clear win.
> 
> If there is a strong appetite for that sort of patch I'm happy to do it.
> 
> Regards,
> Simon
> 

Couple of thoughts:
  - Macro the definition of show_boot_progress() so it accepts a (const
    char *) argument if CONFIG_BOOTSTAGE is defined
  - Change BOOTSTAGE_COUNT to CONFIG_MAX_BOOTSTAGE_RECORDS
  - Any call to show_boot_progress() with a non-null second argument
    causes it to be logged in the next available bootstage record
  - After the last bootstage record is filled, no further calls to
    show_boot_progress() cause logging to the bootstage records
  - Instead of CONFIG_BOOTSTAGE_REPORT, create a command which dumps the
    contents of the bootstage records

No this is going to result in a big patch (every instance of
show_boot_progress() will need to be touched to at least add NULL as the
second parameter - Maintainers can add better text later ;)

Regards,

Graeme