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Re: [PATCH] kill prom_printf

To: Ladislav Michl <ladis@linux-mips.org>
Subject: Re: [PATCH] kill prom_printf
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Tue, 17 Jun 2003 14:14:55 +0200 (MET DST)
Cc: Juan Quintela <quintela@trasno.org>, linux-mips@linux-mips.org
In-reply-to: <20030617085346.A27590@ftp.linux-mips.org>
Organization: Technical University of Gdansk
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
On Tue, 17 Jun 2003, Ladislav Michl wrote:

> Idea is to have only one way for printing kernel messages. In case of Indy,
> O2 and SNI RM200 "arc" console will do it. Here you can find where should
> be early console initialized:
> http://marc.theaimsgroup.com/?l=linux-kernel&m=105519188505235&w=2
> As Juan pointed out setup for such console is actually a nop and one is
> supposed to enable this feature only when debugging kernel. DEC prom console

 That's a valid point, as long as enabling it does not require a
reconfiguration.

> however needs some setup to determine REX entry points. early console is
> currently used on sh, alpha, x86_64 and ia64 architectures. Btw, see comment
> at the top of arch/sparc/prom/printf.c

 The DEC's entry points are a part of the problem only -- to support a
generic kernel, we need to move early_printk setup after setup_arch(), as
the level of variation is huge then.. 

 There is also that minor implementation problem -- how to pass varargs
from printk() to ROM's printf()?  At least the firmware of the DECstation
implements a full-featured printf() as in the C library. 

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +


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