on x86 arch, startup_32 is jumped from where?

Richard.Yang · 08-11-2011, 04:45 AM

by searching the code in arch/x86, I found the definition of startup_32
in boot/compressed/head_32.S.

But I couldn't find where it jumps from.
Could some one tell me where ?

and I found there are two startup_32 another in kernel/head_32.S.
where could I found more detail?

Richard.Yang · 08-11-2011, 08:10 PM

from the bootloader?

syg00 · 08-11-2011, 08:28 PM

They both get called.
I found this a great book for this sort of thing.
Couple of years old now, but still o.k. - around the timeframe CFS went into mainline IIRC.

Edit: - just remembered this link too. Well worth a read.

bsat · 08-12-2011, 12:17 AM

This article gives the sequence of calls during boot.

http://www.ibm.com/developerworks/li...y/l-linuxboot/

Richard.Yang · 08-12-2011, 01:06 AM

Your links are very helpful.
Let me read them first.

Richard.Yang · 08-16-2011, 09:05 AM

I read the code in arch/x86/boot/header.S for latest kernel code.

The code in
bootsect_start:
# Normalize the start address
ljmp $BOOTSEG, $start2
while BOOTSET is defined
BOOTSEG = 0x07C0 /* original address of boot-sector */

so header.S is compiled and move to this location?
I think this is the location where MBR will be loaded?

And the start() function mentioned in the article is changed to __start()?
Than who take the responsibility to jump to here?
This is actually 512 bytes after bootsect_start.

Richard.Yang · 08-17-2011, 08:18 PM

Also, I am wondering whether I could just write the first 512 bytes into a floppy disk.
to make a bootable device.