Re: [PATCH 0/4] Atari kernel-in-FastRAM patches, take three

Geert Uytterhoeven
2014-04-01T08:24:00Z

Hi Michael,

On Tue, Apr 1, 2014 at 10:12 AM, schmitz
<schmitz@biophys.uni-duesseldorf.de> wrote:
> While poking around in head.S, I came across a comment that stated the
> second page at the start of the kernel is used for the kernel page dir -
> that is the second page of virtual address space (FastRAM, in the case we
> care about here), not physcial address space, right?

The kernel is loaded in the second page of RAM. Initially, this page just
contains a few branches and the bootinfo versions. The code jumps to
_start, and the second page is reused for the kernel page dir:

ENTRY(_stext)
bras 1f /* Jump over bootinfo version numbers */
.long BOOTINFOV_MAGIC
.long MACH_AMIGA, AMIGA_BOOTI_VERSION
....
1: jra __start

.equ kernel_pg_dir,_stext

.equ .,_stext+PAGESIZE

ENTRY(_start)
jra __start
__INIT
ENTRY(__start)

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds