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[core] display a notice about Legacy in the protective MBR for GPT

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* This should help Windows users who create a GPT/UEFI drive and try to use it in BIOS/Legacy
* Also make sure that we take into account the split space for both "SELECT" and "DOWNLOAD"
This commit is contained in:
Pete Batard 2019-03-16 13:01:55 +00:00
parent 789373ed59
commit 28c1d6eb31
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GPG key ID: 38E0CF5E69EDD671
11 changed files with 200 additions and 10 deletions
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100
res/mbr/gpt.S Normal file
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/********************************************************************************/
/* GPT - A protective MBR that displays a notice if a user attempts to boot a */
/* GPT drive in BIOS/Legacy mode. */
/* */
/* Copyright (c) 2019 Pete Batard <pete@akeo.ie> */
/* */
/* 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 3 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, see <http://www.gnu.org/licenses/>. */
/* */
/********************************************************************************/
/********************************************************************************/
/* GNU Assembler Settings: */
/********************************************************************************/
.intel_syntax noprefix
.code16
/********************************************************************************/
/********************************************************************************/
/* Constants: */
/********************************************************************************/
MBR_ADDR = 0x7c00
MBR_SIZE = 0x200
MBR_RESERVED = 0x1b8 # Start of the reserved section (partition table, etc.)
PT_MAX = 0x04 # Number of partition entries in the partition table
PT_ENTRY_SIZE = 0x10 # Size of a partition entry in the partition table
/********************************************************************************/
/* MBR: This section resides at 0x00007c00 and is exactly 512 bytes */
/********************************************************************************/
.section main, "ax"
.globl mbr
mbr:
inc cx
dec bx
inc bp
dec di
cld
xor ax, ax
mov ds, ax
mov si, offset sep
call print_string
mov si, offset hdr
call print_string
mov si, offset sep
call print_string
mov si, offset txt
call print_string
hlt
print_string:
lodsb
cmp al, 0x00
jz 0f
mov ah, 0x0e
mov bx, 0x0007
int 0x10
jmp print_string
0: ret
/********************************************************************************/
/* Data section */
/********************************************************************************/
sep:
.string "****************************************\r\n"
hdr:
.string "*** ERROR: LEGACY BOOT OF UEFI MEDIA ***\r\n"
txt:
.ascii "\r\n" \
"This drive can only boot in UEFI mode.\r\n" \
"It can not boot in BIOS/Legacy mode.\r\n" \
"\r\n" \
"If you want to boot this drive in BIOS/Legacy mode, you\r\n" \
"should recreate it in Rufus using the following settings:\r\n" \
"* Partition scheme -> MBR\r\n" \
"* Target system -> BIOS...\r\n" \
"\0"
/********************************************************************************/
/* From offset 0x1b8, the MBR contains the partition table and signature data */
/********************************************************************************/
.org MBR_RESERVED
disk_signature:
.space 0x04
filler:
.space 0x02
partition_table:
.space PT_ENTRY_SIZE * PT_MAX
mbr_signature:
.word 0xAA55

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res/mbr/gpt.bin Normal file
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