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i386 loading from flash
- From: Tim michals <tcmichals at yahoo dot com>
- To: ecos-discuss at sourceware dot org
- Date: Wed, 13 Sep 2006 07:53:35 -0700 (PDT)
- Subject: [ECOS] i386 loading from flash
I'm looking at loading ecos from ROM for a SC520, the
romboot.S assumes a BIOS? because it is call video
memory and loading the descriptor from ROM to RAM
without setting RAM?
Can the GDT descriptor be in ROM, instead of creating
the header in RAM use the header stored in ROM?
movw %0xFFa0,%di //assuming the header starts at
0xffA0
# load GDTR
lgdt %cs:di
.........rest of startup......
.align 4, 0xCC
desc:
.word 0x0032
.word 0xFFA0 //address in ROM
.word 0x000f
.word 0
.word 0
.word 0
gdtStart:
/* Selector 0x00 == invalid. */
.word 0x0000
.word 0x0000
.byte 0x00
.byte 0x00
.byte 0x00
.byte 0x00
/* Selector 0x08 == code. */
.word 0xFFFF
.word 0x0000
.byte 0x00
.byte 0x9B
.byte 0xCF
.byte 0x00
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