Messages in this thread |  | | From | Keith Owens <> | Subject | Re: [DOC] Debugging early kernel hangs | Date | Fri, 22 Sep 2000 10:04:34 +1100 |
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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/
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