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Re: [PATCH] Kernel support for VESA Bios Extension
|
From: |
Vesa Jääskeläinen |
|
Subject: |
Re: [PATCH] Kernel support for VESA Bios Extension |
|
Date: |
Fri, 15 Jul 2005 19:47:32 +0300 |
|
User-agent: |
Mozilla Thunderbird (Windows/20050412) |
Marco Gerards wrote:
+typedef grub_uint32_t grub_vbe_farptr_t;
+typedef grub_uint32_t grub_vbe_physptr_t;
+typedef grub_uint32_t grub_vbe_status_t;
Please use a single space before the type name.
Done.
+struct grub_vbe_mode_info_block
+{
+ /* Mandory information for all VBE revisions */
After the comment add a `.' and two spaces instead of one. This is
true for all comments.
Odd... Especially that two spaces. But I don't want to start another
"war" with this ;)... So I try to adapt.
+ /*
+ * Reserved field to make structure to be 256 bytes long, VESA BIOS
+ * Extension 3.0 Specification says to reserve 189 bytes here but
+ * that doesn't make structure to be 256 bytes. So additional one is
+ * added here.
+ */
I personally prefer not using that many `*'s and believe it is not in
the GCS. But I think Okuji uses this as well, but I don't. Perhaps
we need our own guidelines for such things, I think consistency is
important. Okuji, what you you think?
Now it's modified a bit.
+ grub_uint8_t reserved4[189+1];
Please put spaces around operators. So this should be:
grub_uint8_t reserved4[189 + 1]
Done.
* 31 24 19 16 7 0
* ------------------------------------------------------------
* | | |B| |A| | | |1|0|E|W|A| |
- * | BASE 31..24 |G|/|0|V| LIMIT |P|DPL| TYPE | BASE 23:16 |
+ * | BASE 31..24 |G|/|L|V| LIMIT |P|DPL| TYPE | BASE 23:16 | 4
* | | |D| |L| 19..16| | |1|1|C|R|A| |
* ------------------------------------------------------------
* | | |
- * | BASE 15..0 | LIMIT 15..0 |
+ * | BASE 15..0 | LIMIT 15..0 | 0
* | | |
* ------------------------------------------------------------
*
What is this? Is this copied from (copyrighted) documentation?
It was there already and I just added x86-64 specific flag there and
some helpers (4 and 0) to make it easier to read records correctly. I am
not sure what is it's origin as it was there already, but as you could
guess, it looks similar as in Intel's software developers guide and I
would assume that it looks similar also in AMD's.
It can of course be removed completely in the commit if required to be.
To me it seemed line some lines were too long. Please keep in mind it
should be all readable on a 80 columns width terminal according to the
GCS.
I can see if I can split them more nicely if they are too long. But the
problem is how to split them so that they are conforming the GCS on that
:). But let's see.
I will be gone this weekend. After the weekend I will try to
understand the patch and proofread the assembler code. But my x86
assembly is *very* rusty, so I hope someone else can review this patch
because I am afraid when it comes to assembler my opinion is not worth
a bit. ;)
Ok.
I have attached yet another patch with some formatting changes.
Thanks,
Vesa Jääskeläinen
diff -ruN grub2/ChangeLog grub2.vbe/ChangeLog
--- grub2/ChangeLog 2005-07-13 01:36:43.000000000 +0300
+++ grub2.vbe/ChangeLog 2005-07-17 13:10:20.259773072 +0300
@@ -1,3 +1,21 @@
+2005-07-15 Vesa Jaaskelainen <address@hidden>
+
+ * conf/i386-pc.rmk (kernel_img_HEADERS): Added machine/vbe.h.
+ * kern/i386/pc/startup.S: Updated Global Descriptor table's
+ descriptions.
+ (grub_vbe_get_controller_info): New function.
+ (grub_vbe_get_mode_info): Likewise.
+ (grub_vbe_set_mode): Likewise.
+ (grub_vbe_get_mode): Likewise.
+ (grub_vbe_set_memory_window): Likewise.
+ (grub_vbe_get_memory_window): Likewise.
+ (grub_vbe_set_scanline_length): Likewise.
+ (grub_vbe_get_scanline_length): Likewise.
+ (grub_vbe_set_display_start): Likewise.
+ (grub_vbe_get_display_start): Likewise.
+ (grub_vbe_set_palette_data): Likewise.
+ * include/grub/i386/pc/vbe.h: New file.
+
2005-07-12 Hollis Blanchard <address@hidden>
* disk/powerpc/ieee1275/ofdisk.c (grub_ofdisk_open): dprintf the
diff -ruN grub2/conf/i386-pc.rmk grub2.vbe/conf/i386-pc.rmk
--- grub2/conf/i386-pc.rmk 2005-07-10 10:57:49.000000000 +0300
+++ grub2.vbe/conf/i386-pc.rmk 2005-07-15 18:10:05.000000000 +0300
@@ -33,7 +33,8 @@
file.h fs.h kernel.h loader.h misc.h mm.h net.h rescue.h symbol.h \
term.h types.h machine/biosdisk.h machine/boot.h \
machine/console.h machine/init.h machine/memory.h \
- machine/loader.h partition.h pc_partition.h machine/time.h machine/vga.h
+ machine/loader.h partition.h pc_partition.h machine/time.h
machine/vga.h \
+ machine/vbe.h
kernel_img_CFLAGS = $(COMMON_CFLAGS)
kernel_img_ASFLAGS = $(COMMON_ASFLAGS)
kernel_img_LDFLAGS = -nostdlib -Wl,-N,-Ttext,8200
diff -ruN grub2/include/grub/i386/pc/vbe.h grub2.vbe/include/grub/i386/pc/vbe.h
--- grub2/include/grub/i386/pc/vbe.h 1970-01-01 02:00:00.000000000 +0200
+++ grub2.vbe/include/grub/i386/pc/vbe.h 2005-07-17 13:38:11.675679232
+0300
@@ -0,0 +1,184 @@
+/*
+ * GRUB -- GRand Unified Bootloader
+ * Copyright (C) 2005 Free Software Foundation, Inc.
+ *
+ * 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef GRUB_VBE_MACHINE_HEADER
+#define GRUB_VBE_MACHINE_HEADER 1
+
+#include <grub/symbol.h>
+#include <grub/types.h>
+
+/* Note:
+
+ Please refer to VESA BIOS Extension 3.0 Specification for more descriptive
+ meanings of following structures and how they should be used.
+
+ I have tried to maintain field name comatibility against specification
+ while following naming convetions used in GRUB. */
+
+typedef grub_uint32_t grub_vbe_farptr_t;
+typedef grub_uint32_t grub_vbe_physptr_t;
+typedef grub_uint32_t grub_vbe_status_t;
+
+struct grub_vbe_info_block
+{
+ grub_uint8_t signature[4];
+ grub_uint16_t version;
+
+ grub_vbe_farptr_t oem_string_ptr;
+ grub_uint32_t capabilities;
+ grub_vbe_farptr_t video_mode_ptr;
+ grub_uint16_t total_memory;
+
+ grub_uint16_t oem_software_rev;
+ grub_vbe_farptr_t oem_vendor_name_ptr;
+ grub_vbe_farptr_t oem_product_name_ptr;
+ grub_vbe_farptr_t oem_product_rev_ptr;
+
+ grub_uint8_t reserved[222];
+
+ grub_uint8_t oem_data[256];
+} __attribute__ ((packed));
+
+struct grub_vbe_mode_info_block
+{
+ /* Mandory information for all VBE revisions. */
+ grub_uint16_t mode_attributes;
+ grub_uint8_t win_a_attributes;
+ grub_uint8_t win_b_attributes;
+ grub_uint16_t win_granularity;
+ grub_uint16_t win_size;
+ grub_uint16_t win_a_segment;
+ grub_uint16_t win_b_segment;
+ grub_vbe_farptr_t win_func_ptr;
+ grub_uint16_t bytes_per_scan_line;
+
+ /* Mandory information for VBE 1.2 and above. */
+ grub_uint16_t x_resolution;
+ grub_uint16_t y_resolution;
+ grub_uint8_t x_char_size;
+ grub_uint8_t y_char_size;
+ grub_uint8_t number_of_planes;
+ grub_uint8_t bits_per_pixel;
+ grub_uint8_t number_of_banks;
+ grub_uint8_t memory_model;
+ grub_uint8_t bank_size;
+ grub_uint8_t number_of_image_pages;
+ grub_uint8_t reserved;
+
+ /* Direct Color fields (required for direct/6 and YUV/7 memory models). */
+ grub_uint8_t red_mask_size;
+ grub_uint8_t red_field_position;
+ grub_uint8_t green_mask_size;
+ grub_uint8_t green_field_position;
+ grub_uint8_t blue_mask_size;
+ grub_uint8_t blue_field_position;
+ grub_uint8_t rsvd_mask_size;
+ grub_uint8_t rsvd_field_position;
+ grub_uint8_t direct_color_mode_info;
+
+ /* Mandory information for VBE 2.0 and above. */
+ grub_vbe_physptr_t phys_base_addr;
+ grub_uint32_t reserved2;
+ grub_uint16_t reserved3;
+
+ /* Mandory information for VBE 3.0 and above. */
+ grub_uint16_t lin_bytes_per_scan_line;
+ grub_uint8_t bnk_number_of_image_pages;
+ grub_uint8_t lin_number_of_image_pages;
+ grub_uint8_t lin_red_mask_size;
+ grub_uint8_t lin_red_field_position;
+ grub_uint8_t lin_green_mask_size;
+ grub_uint8_t lin_green_field_position;
+ grub_uint8_t lin_blue_mask_size;
+ grub_uint8_t lin_blue_field_position;
+ grub_uint8_t lin_rsvd_mask_size;
+ grub_uint8_t lin_rsvd_field_position;
+ grub_uint32_t max_pixel_clock;
+
+ /* Reserved field to make structure to be 256 bytes long, VESA BIOS
+ Extension 3.0 Specification says to reserve 189 bytes here but
+ that doesn't make structure to be 256 bytes. So additional one is
+ added here. */
+ grub_uint8_t reserved4[189 + 1];
+} __attribute__ ((packed));
+
+struct grub_vbe_crtc_info_block
+{
+ grub_uint16_t horizontal_total;
+ grub_uint16_t horizontal_sync_start;
+ grub_uint16_t horizontal_sync_end;
+ grub_uint16_t vertical_total;
+ grub_uint16_t vertical_sync_start;
+ grub_uint16_t vertical_sync_end;
+ grub_uint8_t flags;
+ grub_uint32_t pixel_clock;
+ grub_uint16_t refresh_rate;
+ grub_uint8_t reserved[40];
+} __attribute__ ((packed));
+
+struct grub_vbe_palette_data
+{
+ grub_uint8_t blue;
+ grub_uint8_t green;
+ grub_uint8_t red;
+ grub_uint8_t aligment;
+} __attribute__ ((packed));
+
+/* Call VESA BIOS 0x4f00 to get VBE Controller Information, return status. */
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_get_controller_info) (struct
grub_vbe_info_block *controller_info);
+
+/* Call VESA BIOS 0x4f01 to get VBE Mode Information, return status. */
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_get_mode_info) (grub_uint32_t mode,
+ struct
grub_vbe_mode_info_block *mode_info);
+
+/* Call VESA BIOS 0x4f02 to set video mode, return status. */
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_set_mode) (grub_uint32_t mode,
+ struct
grub_vbe_crtc_info_block *crtc_info);
+
+/* Call VESA BIOS 0x4f03 to return current VBE Mode, return status. */
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_get_mode) (grub_uint32_t *mode);
+
+/* Call VESA BIOS 0x4f05 to set memory window, return status. */
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_set_memory_window) (grub_uint32_t
window,
+ grub_uint32_t
position);
+
+/* Call VESA BIOS 0x4f05 to return memory window, return status. */
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_get_memory_window) (grub_uint32_t
window,
+ grub_uint32_t
*position);
+
+/* Call VESA BIOS 0x4f06 to set scanline length (in bytes), return status. */
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_set_scanline_length) (grub_uint32_t
length);
+
+/* Call VESA BIOS 0x4f06 to return scanline length (in bytes), return status.
*/
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_get_scanline_length) (grub_uint32_t
*length);
+
+/* Call VESA BIOS 0x4f07 to set display start, return status. */
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_set_display_start) (grub_uint32_t x,
+ grub_uint32_t y);
+
+/* Call VESA BIOS 0x4f07 to get display start, return status. */
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_get_display_start) (grub_uint32_t *x,
+ grub_uint32_t *y);
+
+/* Call VESA BIOS 0x4f09 to set palette data, return status. */
+grub_vbe_status_t EXPORT_FUNC(grub_vbe_set_palette_data) (grub_uint32_t
color_count,
+ grub_uint32_t
start_index,
+ struct
grub_vbe_palette_data *palette_data);
+
+#endif /* ! GRUB_VBE_MACHINE_HEADER */
diff -ruN grub2/kern/i386/pc/startup.S grub2.vbe/kern/i386/pc/startup.S
--- grub2/kern/i386/pc/startup.S 2004-04-04 16:46:02.000000000 +0300
+++ grub2.vbe/kern/i386/pc/startup.S 2005-07-17 13:28:56.934012784 +0300
@@ -1,6 +1,6 @@
/*
* GRUB -- GRand Unified Bootloader
- * Copyright (C) 1999,2000,2001,2002,2003 Free Software Foundation, Inc.
+ * Copyright (C) 1999,2000,2001,2002,2003,2005 Free Software Foundation, Inc.
*
* 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
@@ -219,11 +219,11 @@
* 31 24 19 16 7 0
* ------------------------------------------------------------
* | | |B| |A| | | |1|0|E|W|A| |
- * | BASE 31..24 |G|/|0|V| LIMIT |P|DPL| TYPE | BASE 23:16 |
+ * | BASE 31..24 |G|/|L|V| LIMIT |P|DPL| TYPE | BASE 23:16 | 4
* | | |D| |L| 19..16| | |1|1|C|R|A| |
* ------------------------------------------------------------
* | | |
- * | BASE 15..0 | LIMIT 15..0 |
+ * | BASE 15..0 | LIMIT 15..0 | 0
* | | |
* ------------------------------------------------------------
*
@@ -236,19 +236,31 @@
.word 0, 0
.byte 0, 0, 0, 0
- /* code segment */
+ /* -- code segment --
+ * base = 0x00000000, limit = 0xFFFFF (4 KiB Granularity), present
+ * type = 32bit code execute/read, DPL = 0
+ */
.word 0xFFFF, 0
.byte 0, 0x9A, 0xCF, 0
- /* data segment */
+ /* -- data segment --
+ * base = 0x00000000, limit 0xFFFFF (4 KiB Granularity), present
+ * type = 32 bit data read/write, DPL = 0
+ */
.word 0xFFFF, 0
.byte 0, 0x92, 0xCF, 0
- /* 16 bit real mode CS */
+ /* -- 16 bit real mode CS --
+ * base = 0x00000000, limit 0x0FFFF (1 B Granularity), present
+ * type = 16 bit code execute/read only/conforming, DPL = 0
+ */
.word 0xFFFF, 0
.byte 0, 0x9E, 0, 0
- /* 16 bit real mode DS */
+ /* -- 16 bit real mode DS --
+ * base = 0x00000000, limit 0x0FFFF (1 B Granularity), present
+ * type = 16 bit data read/write, DPL = 0
+ */
.word 0xFFFF, 0
.byte 0, 0x92, 0, 0
@@ -1594,3 +1606,415 @@
popl %ebx
popl %ebp
ret
+
+/*
+ * grub_vbe_status_t grub_vbe_get_controller_info (struct grub_vbe_info_block
*controller_info)
+ *
+ * Register allocations for parameters:
+ * %eax *controller_info
+ */
+FUNCTION(grub_vbe_get_controller_info)
+ pushl %ebp
+ pushl %edi
+
+ movw %ax, %di /* Store *controller_info to %edx:%di. */
+ xorw %ax, %ax
+ shrl $4, %eax
+ mov %eax, %edx /* prot_to_real destroys %eax. */
+
+ call prot_to_real
+ .code16
+
+ pushw %es
+
+ movw %dx, %es /* *controller_info is now on %es:%di. */
+ movw $0x4f00, %ax
+ int $0x10
+
+ movw %ax, %dx /* real_to_prot destroys %eax. */
+
+ popw %es
+
+ DATA32 call real_to_prot
+ .code32
+
+ movl %edx, %eax
+ andl $0x0FFFF, %eax /* Return value in %eax. */
+
+ popl %edi
+ popl %ebp
+ ret
+
+/*
+ * grub_vbe_status_t grub_vbe_get_mode_info (grub_uint32_t mode,
+ * struct grub_vbe_mode_info_block
*mode_info)
+ *
+ * Register allocations for parameters:
+ * %eax mode
+ * %edx *mode_info
+ */
+FUNCTION(grub_vbe_get_mode_info)
+ pushl %ebp
+ pushl %edi
+
+ movl %eax, %ecx /* Store mode number to %ecx. */
+
+ movw %dx, %di /* Store *mode_info to %edx:%di. */
+ xorw %dx, %dx
+ shrl $4, %edx
+
+ call prot_to_real
+ .code16
+
+ pushw %es
+
+ movw %dx, %es /* *mode_info is now on %es:%di. */
+ movw $0x4f01, %ax
+ int $0x10
+
+ movw %ax, %dx /* real_to_prot destroys %eax. */
+
+ popw %es
+
+ DATA32 call real_to_prot
+ .code32
+
+ movl %edx, %eax
+ andl $0x0FFFF, %eax /* Return value in %eax. */
+
+ popl %edi
+ popl %ebp
+ ret
+
+/*
+ * grub_vbe_status_t grub_vbe_set_mode (grub_uint32_t mode,
+ * struct grub_vbe_crtc_info_block
*crtc_info)
+ *
+ * Register allocations for parameters:
+ * %eax mode
+ * %edx *crtc_info
+ */
+FUNCTION(grub_vbe_set_mode)
+ pushl %ebp
+ pushl %ebx
+
+ movl %eax, %ebx /* Store mode in %ebx. */
+
+ movw %dx, %di /* Store *crtc_info to %edx:%di. */
+ xorw %dx, %dx
+ shrl $4, %edx
+
+ call prot_to_real
+ .code16
+
+ pushw %es
+
+ movw %dx, %es /* *crtc_info is now on %es:%di. */
+
+ movw $0x4f02, %ax
+ int $0x10
+
+ movw %ax, %dx /* real_to_prot destroys %eax. */
+
+ popw %es
+
+ DATA32 call real_to_prot
+ .code32
+
+ movw %dx, %ax
+ andl $0xFFFF, %eax /* Return value in %eax. */
+
+ popl %ebx
+ popl %ebp
+ ret
+
+/*
+ * grub_vbe_status_t grub_vbe_get_mode (grub_uint32_t *mode)
+ *
+ * Register allocations for parameters:
+ * %eax *mode
+ */
+FUNCTION(grub_vbe_get_mode)
+ pushl %ebp
+ pushl %ebx
+ pushl %eax /* Push *mode to stack. */
+
+ call prot_to_real
+ .code16
+
+ movw $0x4f03, %ax
+ int $0x10
+
+ movw %ax, %dx /* real_to_prot destroys %eax. */
+
+ DATA32 call real_to_prot
+ .code32
+
+ popl %edi /* Pops *mode from stack to %edi. */
+ andl $0xFFFF, %ebx
+ movl %ebx, (%edi)
+
+ movw %dx, %ax
+ andl $0xFFFF, %eax /* Return value in %eax. */
+
+ popl %ebx
+ popl %ebp
+ ret
+
+/*
+ * grub_vbe_status_t grub_vbe_set_memory_window (grub_uint32_t window,
+ * grub_uint32_t position);
+ *
+ * Register allocations for parameters:
+ * %eax window
+ * %edx position
+ */
+FUNCTION(grub_vbe_set_memory_window)
+ pushl %ebp
+ pushl %ebx
+
+ movl %eax, %ebx
+
+ call prot_to_real
+ .code16
+
+ movw $0x4f05, %ax
+ andw $0x00ff, %bx /* BL = window, BH = 0, Set memory window. */
+ int $0x10
+
+ movw %ax, %dx /* real_to_prot destroys %eax. */
+
+ DATA32 call real_to_prot
+ .code32
+
+ movw %dx, %ax
+ andl $0xFFFF, %eax /* Return value in %eax. */
+
+ popl %ebx
+ popl %ebp
+ ret
+
+/*
+ * grub_vbe_status_t grub_vbe_get_memory_window (grub_uint32_t window,
+ * grub_uint32_t *position);
+ *
+ * Register allocations for parameters:
+ * %eax window
+ * %edx *position
+ */
+FUNCTION(grub_vbe_get_memory_window)
+ pushl %ebp
+ pushl %ebx
+ pushl %edx /* Push *position to stack. */
+
+ movl %eax, %ebx /* Store window in %ebx. */
+
+ call prot_to_real
+ .code16
+
+ movw $0x4f05, %ax
+ andw $0x00ff, %bx /* BL = window. */
+ orw $0x0100, %bx /* BH = 1, Get memory window. */
+ int $0x10
+
+ movw %ax, %bx /* real_to_prot destroys %eax. */
+
+ DATA32 call real_to_prot
+ .code32
+
+ popl %edi /* pops *position from stack to %edi. */
+ andl $0xFFFF, %edx
+ movl %edx, (%edi) /* Return position to caller. */
+
+ movw %bx, %ax
+ andl $0xFFFF, %eax /* Return value in %eax. */
+
+ popl %ebx
+ popl %ebp
+ ret
+
+/*
+ * grub_vbe_status_t grub_vbe_set_scanline_length (grub_uint32_t length)
+ *
+ * Register allocations for parameters:
+ * %eax length
+ */
+FUNCTION(grub_vbe_set_scanline_length)
+ pushl %ebp
+ pushl %ebx
+
+ movl %eax, %ecx /* Store length in %ecx. */
+
+ call prot_to_real
+ .code16
+
+ movw $0x4f06, %ax
+ movw $0x0002, %bx /* BL = 2, Set Scan Line in Bytes. */
+ int $0x10
+
+ movw %ax, %dx /* real_to_prot destroys %eax. */
+
+ DATA32 call real_to_prot
+ .code32
+
+ movw %dx, %ax
+ andl $0xFFFF, %eax /* Return value in %eax. */
+
+ popl %ebx
+ popl %ebp
+ ret
+
+/*
+ * grub_vbe_status_t grub_vbe_get_scanline_length (grub_uint32_t *length)
+ *
+ * Register allocations for parameters:
+ * %eax *length
+ */
+FUNCTION(grub_vbe_get_scanline_length)
+ pushl %ebp
+ pushl %ebx
+ pushl %edx /* Push *length to stack. */
+
+ call prot_to_real
+ .code16
+
+ movw $0x4f06, %ax
+ movw $0x0001, %bx /* BL = 1, Get Scan Line Length (in bytes). */
+ int $0x10
+
+ movw %ax, %dx /* real_to_prot destroys %eax. */
+
+ DATA32 call real_to_prot
+ .code32
+
+ popl %edi /* Pops *length from stack to %edi. */
+ andl $0xFFFF, %ebx
+ movl %ebx, (%edi) /* Return length to caller. */
+
+ movw %dx, %ax
+ andl $0xFFFF, %eax /* Return value in %eax. */
+
+ popl %ebx
+ popl %ebp
+ ret
+
+/*
+ * grub_vbe_status_t grub_vbe_set_display_start (grub_uint32_t x,
+ * grub_uint32_t y)
+ *
+ * Register allocations for parameters:
+ * %eax x
+ * %edx y
+ */
+FUNCTION(grub_vbe_set_display_start)
+ pushl %ebp
+ pushl %ebx
+
+ movl %eax, %ecx /* Store x in %ecx. */
+
+ call prot_to_real
+ .code16
+
+ movw $0x4f07, %ax
+ movw $0x0080, %bx /* BL = 80h, Set Display Start
+ during Vertical Retrace. */
+ int $0x10
+
+ movw %ax, %dx /* real_to_prot destroys %eax. */
+
+ DATA32 call real_to_prot
+ .code32
+
+ movw %dx, %ax
+ andl $0xFFFF, %eax /* Return value in %eax. */
+
+ popl %ebx
+ popl %ebp
+ ret
+
+/*
+ * grub_vbe_status_t grub_vbe_get_display_start (grub_uint32_t *x,
+ * grub_uint32_t *y)
+ *
+ * Register allocations for parameters:
+ * %eax *x
+ * %edx *y
+ */
+FUNCTION(grub_vbe_get_display_start)
+ pushl %ebp
+ pushl %ebx
+ pushl %eax /* Push *x to stack. */
+ pushl %edx /* Push *y to stack. */
+
+ call prot_to_real
+ .code16
+
+ movw $0x4f07, %ax
+ movw $0x0001, %bx /* BL = 1, Get Display Start. */
+ int $0x10
+
+ movw %ax, %bx /* real_to_prot destroys %eax. */
+
+ DATA32 call real_to_prot
+ .code32
+
+ popl %edi /* Pops *y from stack to %edi. */
+ andl $0xFFFF, %edx
+ movl %edx, (%edi) /* Return y-position to caller. */
+
+ popl %edi /* Pops *x from stack to %edi. */
+ andl $0xFFFF, %ecx
+ movl %ecx, (%edi) /* Return x-position to caller. */
+
+ movw %bx, %ax
+ andl $0xFFFF, %eax /* Return value in %eax. */
+
+ popl %ebx
+ popl %ebp
+ ret
+
+/*
+ * grub_vbe_status_t grub_vbe_set_palette_data (grub_uint32_t color_count,
+ * grub_uint32_t start_index,
+ * struct grub_vbe_palette_data
*palette_data)
+ *
+ * Register allocations for parameters:
+ * %eax color_count
+ * %edx start_index
+ * %ecx *palette_data
+ */
+FUNCTION(grub_vbe_set_palette_data)
+ pushl %ebp
+ pushl %ebx
+
+ movl %eax, %ebx /* Store color_count in %ebx. */
+
+ movw %cx, %di /* Store *palette_data to %ecx:%di. */
+ xorw %cx, %cx
+ shrl $4, %ecx
+
+ call prot_to_real
+ .code16
+
+ pushw %es
+
+ movw %cx, %es /* *palette_data is now on %es:%di. */
+ movw %bx, %cx /* color_count is now on %cx. */
+
+ movw $0x4f09, %ax
+ xorw %bx, %bx /* BL = 0, Set Palette Data. */
+ int $0x10
+
+ movw %ax, %dx /* real_to_prot destroys %eax. */
+
+ popw %es
+
+ DATA32 call real_to_prot
+ .code32
+
+ movw %dx, %ax
+ andl $0xFFFF, %eax /* Return value in %eax. */
+
+ popl %ebx
+ popl %ebp
+ ret