Re: [PATCH 5/5] arm: boot: store ATAGs structure into DT "/chosen/linux,atags" entry

From: Nicolas Pitre
Date: Fri Nov 27 2015 - 18:29:20 EST


On Fri, 27 Nov 2015, Arnd Bergmann wrote:

> I don't mind creating the /proc/atags compatibility hack from the kernel
> for a DT based N700 kernel, as long as we limit it as much as we can
> to the machines that need it. Leaving a board file for the N700 in place
> that contains the procfs code (and not much more) seems reasonable
> here, as we are talking about a board specific hack and the whole point
> appears to be running unmodified user space.
>
> Regarding how to get the data into the kernel in the first place, my
> preferred choice would still be to have an intermediate bootloader
> such as pxa-impedance-matcher, but I won't complain if others are
> happy enough about putting it into the ATAGS compat code we already
> have, as long as it's limited to the boards we know need it.

Assuming you have a N700 board file for special procfs code, then why
not getting at the atags in memory where the bootloader has put them
directly from that same board file? This way it'll really be limited to
the board we know needs it and the special exception will be contained
to that one file. Amongst the machine specific hooks, there is one that
gets invoked early during boot before those atags are overwritten.


Nicolas
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