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

Wolfgang Denk
2012-11-21T09:30:18Z

Dear Lee Jones,

In message <20121121091717.GG28265@gmail.com> you wrote:
> Hi Wolfgang,
>
> > In message <1353422034-28107-6-git-send-email-lee.jones@linaro.org> you wrote:
> > > 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.

> > 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.

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.

Best regards,

Wolfgang Denk

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