This is a note to let you know that I've just added the patch titled
x86/boot: Remove the 'bugger off' message
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-boot-remove-the-bugger-off-message.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 768171d7ebbce005210e1cf8456f043304805c15 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@xxxxxxxxxx>
Date: Tue, 12 Sep 2023 09:00:55 +0000
Subject: x86/boot: Remove the 'bugger off' message
From: Ard Biesheuvel <ardb@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: H. Peter Anvin (Intel) <hpa@xxxxxxxxx>
Link: https://lore.kernel.org/r/20230912090051.4014114-21-ardb@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/boot/header.S | 49 -------------------------------------------------
arch/x86/boot/setup.ld | 7 ++++---
2 files changed, 4 insertions(+), 52 deletions(-)
--- a/arch/x86/boot/header.S
+++ b/arch/x86/boot/header.S
@@ -38,64 +38,15 @@ SYSSEG = 0x1000 /* historical load add
.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
--- 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) }
Patches currently in stable-queue which might be from ardb@xxxxxxxxxx are
queue-6.6/x86-boot-increase-section-and-file-alignment-to-4k-512.patch
queue-6.6/x86-boot-derive-file-size-from-_edata-symbol.patch
queue-6.6/x86-boot-construct-pe-coff-.text-section-from-assembler.patch
queue-6.6/x86-boot-split-off-pe-coff-.data-section.patch
queue-6.6/kallsyms-ignore-armv4-thunks-along-with-others.patch
queue-6.6/x86-efi-drop-alignment-flags-from-pe-section-headers.patch
queue-6.6/x86-boot-drop-references-to-startup_64.patch
queue-6.6/x86-efistub-use-1-1-file-memory-mapping-for-pe-coff-.compat-section.patch
queue-6.6/x86-boot-drop-pe-coff-.reloc-section.patch
queue-6.6/x86-boot-set-efi-handover-offset-directly-in-header-asm.patch
queue-6.6/x86-efi-drop-efi-stub-.bss-from-.data-section.patch
queue-6.6/x86-efi-disregard-setup-header-of-loaded-image.patch
queue-6.6/x86-boot-grab-kernel_info-offset-from-zoffset-header-directly.patch
queue-6.6/x86-boot-drop-redundant-code-setting-the-root-device.patch
queue-6.6/x86-boot-remove-the-bugger-off-message.patch
queue-6.6/x86-boot-omit-compression-buffer-from-pe-coff-image-memory-footprint.patch
queue-6.6/x86-boot-define-setup-size-in-linker-script.patch
