[RFC PATCH 00/12] ARM: Decompressor multiplatform support

On Tue, Jul 17, 2012 at 02:31:15PM +0000, Arnd Bergmann wrote:

On Sunday 15 July 2012, Domenico Andreoli wrote:

quoted

My intent is to get rid of uncompress.h and prepare the decompressor
to dynamically select the various machine specific decompressor init
steps, included the selection of the appropriate console driver.

Currently the mainline kernel defines these steps statically and indeed
has some trouble to boot on different boards with the same binary.

What this patch does is allowing the four functions (arch_decomp_setup,
arch_error, putc and flush) currently used to define such static steps
to be packed in quantity and to be selected/executed by the decompressor
accordingly to the machid or DT passed by the boot loader.

I definitely like the implementation, it looks very nicely done with the
driver specific code being right inside of the actual device drivers.

yep, thanks.

I think the main question we have to answer is whether we want to go
this far for the decompressor output. IIRC the last time this was
debated, the argument was made (I don't remember if it was by Russell
or someone else) that the decompressor code is designed to be as simple
as possible and we should add too much complexity in it that would make
it harder to debug when the only purpose of that code is to debug the
decompressor code itself.

I also made this question [0] but probably the message was too long and
nobody bothered to read it fully :)

The question applies almost unchanged for the arch_decomp_setup()/arch_error()
calls. Those could be worthy to preserve and probably less easy to dismiss
than the console ;)

I find it hard to judge what the benefit of your implementation is
compared to the risk of introducing bugs.

Indeed. I can also add that without a sound extraction of console data
from DT, where arm is heading, the thing looks even less appealing.

But I needed to publish it :)

The other part I don't understand is how it relates to the
early_print() infrastructure that has some of the same requirements.

If there is, it's not intentional.

cheers,
Domenico

[0] http://www.spinics.net/lists/arm-kernel/msg177843.html