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SubjectRe: [DOC] Debugging early kernel hangs
On Thu, 21 Sep 2000 18:54:33 -0400 (EDT), 
Byron Stanoszek <> 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>.
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