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authorArd Biesheuvel <ardb@kernel.org>2023-09-12 12:00:55 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2024-02-23 11:25:25 +0300
commitd9b6b6e8d871b6ca8d3c8f0d2bb7f327edaf7a2e (patch)
treef28fba5e27b23d8d6a2bd744d6a2dce04486b773 /arch/x86
parente17a8bf1fb5d655e46a7f67eebe6ab7c1f4232d0 (diff)
downloadlinux-d9b6b6e8d871b6ca8d3c8f0d2bb7f327edaf7a2e.tar.xz
x86/boot: Remove the 'bugger off' message
commit 768171d7ebbce005210e1cf8456f043304805c15 upstream. Ancient (pre-2003) x86 kernels could boot from a floppy disk straight from the BIOS, using a small real mode boot stub at the start of the image where the BIOS would expect the boot record (or boot block) to appear. Due to its limitations (kernel size < 1 MiB, no support for IDE, USB or El Torito floppy emulation), this support was dropped, and a Linux aware bootloader is now always required to boot the kernel from a legacy BIOS. To smoothen this transition, the boot stub was not removed entirely, but replaced with one that just prints an error message telling the user to install a bootloader. As it is unlikely that anyone doing direct floppy boot with such an ancient kernel is going to upgrade to v6.5+ and expect that this boot method still works, printing this message is kind of pointless, and so it should be possible to remove the logic that emits it. Let's free up this space so it can be used to expand the PE header in a subsequent patch. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com> Link: https://lore.kernel.org/r/20230912090051.4014114-21-ardb@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/boot/header.S49
-rw-r--r--arch/x86/boot/setup.ld7
2 files changed, 4 insertions, 52 deletions
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 8c8148d751c6..b24fa50a9898 100644
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -38,64 +38,15 @@ SYSSEG = 0x1000 /* historical load address >> 4 */
.code16
.section ".bstext", "ax"
-
- .global bootsect_start
-bootsect_start:
#ifdef CONFIG_EFI_STUB
# "MZ", MS-DOS header
.word MZ_MAGIC
-#endif
-
- # Normalize the start address
- ljmp $BOOTSEG, $start2
-
-start2:
- movw %cs, %ax
- movw %ax, %ds
- movw %ax, %es
- movw %ax, %ss
- xorw %sp, %sp
- sti
- cld
-
- movw $bugger_off_msg, %si
-
-msg_loop:
- lodsb
- andb %al, %al
- jz bs_die
- movb $0xe, %ah
- movw $7, %bx
- int $0x10
- jmp msg_loop
-
-bs_die:
- # Allow the user to press a key, then reboot
- xorw %ax, %ax
- int $0x16
- int $0x19
-
- # int 0x19 should never return. In case it does anyway,
- # invoke the BIOS reset code...
- ljmp $0xf000,$0xfff0
-
-#ifdef CONFIG_EFI_STUB
.org 0x38
#
# Offset to the PE header.
#
.long LINUX_PE_MAGIC
.long pe_header
-#endif /* CONFIG_EFI_STUB */
-
- .section ".bsdata", "a"
-bugger_off_msg:
- .ascii "Use a boot loader.\r\n"
- .ascii "\n"
- .ascii "Remove disk and press any key to reboot...\r\n"
- .byte 0
-
-#ifdef CONFIG_EFI_STUB
pe_header:
.long PE_MAGIC
diff --git a/arch/x86/boot/setup.ld b/arch/x86/boot/setup.ld
index 49546c247ae2..b11c45b9e51e 100644
--- a/arch/x86/boot/setup.ld
+++ b/arch/x86/boot/setup.ld
@@ -10,10 +10,11 @@ ENTRY(_start)
SECTIONS
{
. = 0;
- .bstext : { *(.bstext) }
- .bsdata : { *(.bsdata) }
+ .bstext : {
+ *(.bstext)
+ . = 495;
+ } =0xffffffff
- . = 495;
.header : { *(.header) }
.entrytext : { *(.entrytext) }
.inittext : { *(.inittext) }