[U-Boot] [PATCH 5/8] arm: Add boottime support for the ARM architecture

Wolfgang Denk
2012-11-21T16:05:01Z

Dear Lee Jones,

In message <20121121143928.GA28899@gmail.com> you wrote:
>
> > If you are not interested in such information, then just use
> > appropriate log levels and filtering.
>
> I think the kernel log is the wrong place for this to go. Although,

OK, this is your opinion, then, and I will respect it.

It is my opinion that mechanisms as ATAGS or device tree are
inappropriate for passing any kind of log data to the kernel.

So far, the established way of passing logging information (like
results of Power-On Selft Tests,e tc.) is through a shared log buffer.

> the kernel driver will allow you to print the information in a log
> format by cat'ing <debugfs>/boottime/bootgraph, it's not really
> kernel logging information. It's mearly a collection of trace-points
> containing a timestamp and some means of identification.

I don't see what a kernel driver may be needed for, but for this part
of the discussion this is not relevant anyway.

> Filling the kernel log with lots of trace-points is definitely wrong.

Again, this is your opinion, and I respect it. On the other hand,
what is the kernel log being used for on log level INFO, for example?

> So you're suggesting that we create a userland portion of the driver
> too? I don't think this is acceptable. This tool will be used by
> kernel engineers, who would be more happy taking the information from
> debugfs. At least I know I would.

I do not suggest anything like that. I suggest not to write any
driver at all, nor any other code. I suggest to use existing tools,
as I recommend to reuse existing (standard) methods and protocols
instead of inventing new ones.

Best regards,

Wolfgang Denk

--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
A witty saying proves nothing, but saying something pointless gets
people's attention.