Re: kernel goes dark on boot

[Emmanuel Dreyfus <manu%netbsd.org@localhost>]

On Tue, Apr 04, 2023 at 09:04:02PM +0200, Joerg Sonnenberger wrote:
> Look for beep_on_reset in the ACPI wake code. If your machine has a PC
> speaker emulated, that might be the easiest option:

This is brilliant! 

I moved the beep code at various places in startprog64 in
src/sys/arch/i386/stand/efiboot/bootx64/startprog64.S

Bootstrap code looses ground on rep movsq or rep movsb 
instructions. The beep code before the string copy 
produces sound, it does not if inserted after the string
copy.

startprog64 contains 5 flavor of kernel copy, each using
string copy:
- aligned copy forward
- misaligned copy forward
- aligned copy backward
- byte by byte copy forward (with rep movsb)
- byte by byte copy backward (with rep movsb)

Forcing code path to use any of them produces the same
issue: loose control on rep movs[qb].




-- 
Emmanuel Dreyfus
manu%netbsd.org@localhost