Re: [PATCH] sparc64: Netra AX1105 loses console output while

[David Miller <davem@davemloft.net>]

From: Adrien Mazarguil <maz@p0d.org>
Date: Sun, 7 Nov 2010 14:20:51 +0100

> While trying recent kernels on a Sun Netra AX1105 board, I noticed that the
> boot process stopped before init had a chance to run. Using git bisect, I
> narrowed this regression down to that commit:
 ...
> On this board, the new prom_nbputchar() fails at some point in the boot
> process and no subsequent output is shown. Using either the older function
> in place of this one or a static buffer solve that issue. This seems related
> to this paragraph in the above commit log:
...
> Looks like it is still required by older boards, or maybe something else
> needs to be fixed? This is strange because everything works fine until the
> first call to schedule() just before the last assembly part of switch_to()
> macro.

Thanks for tracking down this problem.

The real issue is that on older boards, passing larger than 32-bit
addresses to prom calls (generally) doesn't work correctly.

That's why using a static variable instead of a kernel stack variable
fixes the problem.

This is a larger can of worms than just these two console I/O
routines, let me do the audit and I'll give you a patch to test.

Thanks!