Re: grub thing

[Aleph One <amerei@gmail.com>]

On Wed, 1 Mar 2006 10:34:11 -0300
Ricardo Nabinger Sanchez <rnsanchez@terra.com.br> wrote:

~Quoting  Aleph One <amerei@gmail.com>
~Sent on  Wed, 1 Mar 2006 07:10:33 +0000
~
~> i'm looking at a disassembly of grub's stage 1. and i wanna know why it
~> need's to CLI before setting up the environment?? i tried to interpret it
~> line by line and this is what i have so far
~
~I'm not an expert, but interruptions must be disabled.  I believe grub
~doesn't install interrupt handlers, and thus a single interrupt would lock
~the machine (as the appropriate handler would likely point to garbage).
~
~would the BIOS (or similar in other architectures) give the processor to
~the bootloader with interrupts disabled already?
~
~> also, since the origin is at 0000:7c00h i figured that must imply that
~> "mov sp, 0x2000" means that the stack starts at 0x7c00+0x2000 = 9c000
~> right?
~
~I guess not.  to get what you described, I would do:
~
~	mov sp, 0x2000
~	add sp, 0x7c00
~
~from your disassembly, I'd expect SP to be 0x2000, counting from 0x0000.

groovy! thanks for clarifying this to me. i kinda got messed up thinking about relating the stack with the 7c000 start address :(

~-- 
~Ricardo Nabinger Sanchez
~GNU/Linux #140696 [http://counter.li.org]
~Slackware Linux + FreeBSD
~
~  Left to themselves, things tend to go from bad to worse.
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