lkml.org 
[lkml]   [2000]   [Sep]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [DOC] Debugging early kernel hangs
Date
On Thu, 21 Sep 2000 18:54:33 -0400 (EDT), 
Byron Stanoszek <gandalf@winds.org> wrote:
>On Fri, 22 Sep 2000, Keith Owens wrote:
>> The idea is to write characters direct to the video screen during
>> booting using a macro called VIDEO_CHAR.
>
>Why not just redirect printk() to output a string of characters one by one
>using VIDEO_CHAR until the console subsystem is initialized. You can use a
>statically defined int to keep track of what row & column you're on. There is
>no need to be so cryptic about the readout.

Overhead and difficulty to use from assembler. VIDEO_CHAR() generates
a single mov instruction, calling printk and looping to do output does
a lot more code. You can do the equivalent of VIDEO_CHAR direct from
assembler without disturbing any registers, to call printk means saving
registers around the call and constructing text strings in the
assembler code.

</humour>And besides, debugging should be difficult, damn it</humour>.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:38    [W:0.108 / U:2.640 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site