/*
- * U-boot - x86 Startup Code
+ * U-Boot - x86 Startup Code
*
* (C) Copyright 2008-2011
* Graeme Russ, <graeme.russ@gmail.com>
* (C) Copyright 2002,2003
* Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
*
- * See file CREDITS for list of people who contributed to this
- * project.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2 of
- * the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
- * MA 02111-1307 USA
+ * SPDX-License-Identifier: GPL-2.0+
*/
#include <asm/global_data.h>
.code16
.globl start16
start16:
- /*
- * First we let the BSP do some early initialization
- * this code have to map the flash to its final position
- */
- jmp board_init16
-.globl board_init16_ret
-board_init16_ret:
+ /* Save BIST */
+ movl %eax, %ecx
- /* Turn of cache (this might require a 486-class CPU) */
+ /* Set the Cold Boot / Hard Reset flag */
+ movl $GD_FLG_COLD_BOOT, %ebx
+
+ xorl %eax, %eax
+ movl %eax, %cr3 /* Invalidate TLB */
+
+ /* Turn off cache (this might require a 486-class CPU) */
movl %cr0, %eax
orl $(X86_CR0_NW | X86_CR0_CD), %eax
movl %eax, %cr0
/* Flush the prefetch queue */
jmp ff
ff:
- /* Finally jump to the 32bit initialization code */
+
+ /* Finally restore BIST and jump to the 32-bit initialization code */
movw $code32start, %ax
movw %ax, %bp
+ movl %ecx, %eax
o32 cs ljmp *(%bp)
/* 48-bit far pointer */
.word 0 /* limit */
.long 0 /* base */
-/*
- * The following Global Descriptor Table is just enough to get us into
- * 'Flat Protected Mode' - It will be discarded as soon as the final
- * GDT is setup in a safe location in RAM
- */
+ /*
+ * The following Global Descriptor Table is just enough to get us into
+ * 'Flat Protected Mode' - It will be discarded as soon as the final
+ * GDT is setup in a safe location in RAM
+ */
gdt_ptr:
- .word 0x20 /* limit (32 bytes = 4 GDT entries) */
- .long BOOT_SEG + gdt /* base */
+ .word 0x1f /* limit (31 bytes = 4 GDT entries - 1) */
+ .long BOOT_SEG + gdt_rom /* base */
- /* The GDT table ...
+ /* Some CPUs are picky about GDT alignment... */
+ .align 16
+.globl gdt_rom
+gdt_rom:
+ /*
+ * The GDT table ...
*
* Selector Type
* 0x00 NULL
* 0x10 32bit code
* 0x18 32bit data/stack
*/
+ /* The NULL Desciptor - Mandatory */
+ .word 0x0000 /* limit_low */
+ .word 0x0000 /* base_low */
+ .byte 0x00 /* base_middle */
+ .byte 0x00 /* access */
+ .byte 0x00 /* flags + limit_high */
+ .byte 0x00 /* base_high */
-gdt:
- .word 0, 0, 0, 0 /* NULL */
- .word 0, 0, 0, 0 /* unused */
+ /* Unused Desciptor - (matches Linux) */
+ .word 0x0000 /* limit_low */
+ .word 0x0000 /* base_low */
+ .byte 0x00 /* base_middle */
+ .byte 0x00 /* access */
+ .byte 0x00 /* flags + limit_high */
+ .byte 0x00 /* base_high */
- .word 0xFFFF /* 4Gb - (0x100000*0x1000 = 4Gb) */
- .word 0 /* base address = 0 */
- .word 0x9B00 /* code read/exec */
- .word 0x00CF /* granularity = 4096, 386 (+5th nibble of limit) */
+ /*
+ * The Code Segment Descriptor:
+ * - Base = 0x00000000
+ * - Size = 4GB
+ * - Access = Present, Ring 0, Exec (Code), Readable
+ * - Flags = 4kB Granularity, 32-bit
+ */
+ .word 0xffff /* limit_low */
+ .word 0x0000 /* base_low */
+ .byte 0x00 /* base_middle */
+ .byte 0x9b /* access */
+ .byte 0xcf /* flags + limit_high */
+ .byte 0x00 /* base_high */
- .word 0xFFFF /* 4Gb - (0x100000*0x1000 = 4Gb) */
- .word 0x0 /* base address = 0 */
- .word 0x9300 /* data read/write */
- .word 0x00CF /* granularity = 4096, 386 (+5th nibble of limit) */
+ /*
+ * The Data Segment Descriptor:
+ * - Base = 0x00000000
+ * - Size = 4GB
+ * - Access = Present, Ring 0, Non-Exec (Data), Writable
+ * - Flags = 4kB Granularity, 32-bit
+ */
+ .word 0xffff /* limit_low */
+ .word 0x0000 /* base_low */
+ .byte 0x00 /* base_middle */
+ .byte 0x93 /* access */
+ .byte 0xcf /* flags + limit_high */
+ .byte 0x00 /* base_high */