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

Lee Jones
2012-11-21T10:13:10Z

> > > > This patch adds support for passing boot time information to
> > > > the Linus kernel using ATAGS when booting on ARM based devices.
> > >
> > > I implicitly mentioned this before, here it comes clear again:
> >
> > Ah, this has been tried before? Sorry, I didn't know that.
>
> I expolained it in my reply to your cover letter, i.e. in the message
> immediately preceeding the one you replied to here.

So you're telling me off for sending a patch which doesn't agree with
something you've said, despite you saying it _after_ I sent the patch?

Sounds sensible. :)

> > > I dislike the idea of adding such infrastructure in an archittecture
> > > dependent way, knowing from day one that we cannot use this as is for
> > > other architectures, and that the mechanism being used is even going
> > > to go away for this architecutre, too.
> > >
> > > Please come up with a solution that works for all architectures
> > > instead.
> >
> > So I guess Device Tree it is then.
>
> No. The device tree is for passing hardware information to U-Boot and
> the kernel. It is NOT intended for carrying things like debug or
> timing logs. It is not a good idea to misuse such services for things
> they were not made for nor where they fit.

Okay, got it.

> Please use a standard facility, and one designed for such purposes
> like the Linux log buffer for this purpose. As explained, this has
> the added benefit that you don't need to change any Linux code. And
> you can build on the (also existing) show_boot_progress() support in
> U-Boot, so the extesions should actually be really small and pretty
> clear.

When you say log buffer, do you mean __log_buf? Doesn't this contain
logs used for dmesg; thus won't all this crud end up in a user's
dmesg kernel log? Unless there is another log which is used only
for the kernel.

Also, wouldn't I then have to write a text parser to process this
information? Sounds horrendous. Hopefully, I have missed something
and it's actually easier than what I've mentioned.

--
Lee Jones
Linaro ST-Ericsson Landing Team Lead
Linaro.org ? Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog