Date: Wed, 15 Dec 2004 10:43:45 -0800 From: <Vijay.Singh@nokia.com> To: <hackers@freebsd.org> Subject: loading kernel at any physical address Message-ID: <E40595640FD457418D8F9005C2BEC8496456A2@mvebe001.americas.nokia.com>
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Hello all, for a project I am trying to figure out how to boot a FreeBSD kernel loaded at any physical address. Right now the locore.s magic works because the load addres (KERNLOAD) and (KERNBASE) are set such that
#define R(foo) ((foo)-KERNBASE)
macro is able to get the addresses before paging is enabled.
If the loadaddress information is not embedded in defines, then is the following solution expected to work:
.globl _loadaddress /* should be at 16M aligned ??? */
.set _loadaddress,KERNBASE
and then:
NON_GPROF_ENTRY(btext)
nop /* nops for 8 byte alignment */
nop
nop
call 0f
0:
mov 4(%ebp), %eax
add $-8, %eax /* This is actual physical load addr */
add $-0x100000, %eax
subl %eax, _loadaddress /* new kernbase w.r.t load addr */
/* instead of standard 1MB reloc */
and then
#define R(foo) ((foo)- _loadaddress)
One issue might be loadaddress over 16M, but for this problem we can assume that the processor has been in protected mode, so it has access to that space.
Any input on this is highly appreciated.
br
vijay
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