redboot support for executing linux on i386

[Ian Campbell]

Hi,

This patch was posted here an age ago but rejected since it was large
enough to require a copyright assignment. We have now got this all done
so I'm resubmitting now.

This patch adds support for a redboot command which can boot a Linux
bzImage on i386. The command is called 'linux' rather than the more
usual 'exec' since on i386 it is rather more Linux specific than exec is
on other platforms (ARM say). 

The commands works by setting up the Linux parameter region the same as
would normally be done by the Linux real-mode setup code (which relies
on a BIOS), setting up the MMU as for Linux (GDT etc) and then jumping
to the kernel's protected mode entry point. This method has been used to
boot several different kernels from 2.4.18 right up to the current BK
head code this morning.

There are a couple of ChangeLogs

packages/hal/i386/pcmb/current/ChangeLog:

2004-10-29  Ian Campbell  <icampbell@arcom.com>

        * include/pcmb_serial.h, src/pcmb_screen.c: define
        cyg_hal_plf_screen_position() which can be used to get the current
        screen offset. This will be used by the Linux exec code to tell
        Linux where to start printing from.

packages/hal/i386/arch/current/ChangeLog:

2004-10-29  Ian Campbell  <icampbell@arcom.com>

        * cdl/hal_i386.cdl, src/redboot_linux_exec..c: Add a new RedBoot
	command "linux" which executes a Linux zImage or bzImage already
	loaded into RAM.

packages/hal/i386/pc/current/ChangeLog:

2004-10-29  Ian Campbell  <icampbell@arcom.com>

	* cdl/hal_i386_pc.cdl: Define CYGHWR_REDBOOT_I386_TRAMPOLINE_ADDRESS
	to enable booting Linux from RedBoot.

Cheers,
Ian.

-- 
Ian Campbell, Senior Design Engineer
                                        Web: http://www.arcom.com
Arcom, Clifton Road, 			Direct: +44 (0)1223 403 465
Cambridge CB1 7EA, United Kingdom	Phone:  +44 (0)1223 411 200


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