我一直在尝试移植非Linux符合多重引导 0.6.96 标准（多重引导头超过 8 KiB）32 位 elf 内核从 GRUB Legacy 升级到 GRUB2。目前，内核和 GRUB 放在 USB 上，用于通过 BIOS 启动另一台计算机，就像实时 USB 一样。我一直在测试的计算机是 Intel i5 Skylake。以前，GRUB Legacy 能够使用以下配置启动内核：
# grub.cfg
timeout 5
title "USB Boot"
kernel /boot/kernel
boot
对于 GRUB2 我将其更改为：
# grub.cfg
set timeout=5
debug=all
serial --speed=115200
terminal_output --append serial
menuentry "USB Boot" {
set root="(hd0,msdos1)" # USB drive
multiboot /boot/kernel
boot
}
但这会导致 GRUB2 在尝试跳转到内核后出现永远闪烁的光标。
为了实现这一目标，我从头构建了 GRUB2：
wget ftp://ftp.gnu.org/gnu/grub/grub-2.02.tar.gz
tar -xzvf grub-2.02.tar.gz
cd grub-2.02
# Change MULTIBOOT_SEARCH from 8192 to 32708 in include/multiboot.h
./autogen.sh
./configure
最终的输出./configure为：
*******************************************************
GRUB2 will be compiled with following components:
Platform: i386-pc
With devmapper support: No (need libdevmapper header)
With memory debugging: No
With disk cache statistics: No
With boot time statistics: No
efiemu runtime: Yes
grub-mkfont: No (need freetype2 library)
grub-mount: No (need FUSE library)
starfield theme: No (No build-time grub-mkfont)
With libzfs support: No (need zfs library)
Build-time grub-mkfont: No (need freetype2 library)
Without unifont (no build-time grub-mkfont)
With liblzma from -llzma (support for XZ-compressed mips images)
*******************************************************
我制作了 GRUB2 并在 USB 中填充了以下内容：
make -j12
# Some fdisk formating to the USB removed for brevity
sudo mount /dev/sdc1 /mnt # /dev/sdc is the USB GRUB will attempt to boot off of
sudo ./grub-install --no-floppy --boot-directory=/mnt/boot --target=i386-pc --directory=grub-core /dev/sdc
sudo cp grub.cfg /mnt/boot/grub/grub.cfg # grub.cfg is the GRUB2 config file from above
sudo cp kernel /mnt/boot/
sync
sudo umount /mnt
我将 USB 从我的电脑移到测试机上并尝试启动内核。尝试的调试输出如下：
script/script.c:65: free 0xd9d6f8e0
Booting `USB Boot'free 0xd9d6f900
script/script.c:65: free 0xd9d6f920
script/lexer.c:321: token 288 text [setparams]
script/script.c:50: malloc 0xd9d70830
script/script.c:50: malloc 0xd9d70800
script/script.c:163: arglist9d6cee0
script/script.c:50: malloc 0xd9d707d0
script/lexer.c:321: token 289 text []
script/script.c:50: malloc 0xd9d706a0
script/script.c:50: malloc 0xcba8c4a0
script/lexer.c:321: token 289 text [USB Boot]
script/script.c:50: malloc 0xd9d70670
script/script.c:50: malloc 0xd9d70650
script/lexer.c:321: token 289 text []
script/script.c:50: malloc 0xd9d70620
script/script.c:50: malloc 0xcba900d0
script/script.c:163: arglist
script/script.c:50: malloc 0xd9d705f0
script/lexer.c:321: token 259 text [
]
script/script.c:50: malloc 0xd9d705c0
script/script.c:50: malloc 0xd9d705a0
script/script.c:198: cmdline
script/script.c:50: malloc 0xd9d70570
script/lexer.c:321: token 0 text []
script/script.c:50: malloc 0xd9d708d0
script/script.c:50: malloc 0xd9d708b0
script/script.c:294: append command
script/script.c:50: malloc 0xd9d70550
script/script.c:65: free 0xd9d70550
script/script.c:65: free 0xd9d708b0
script/script.c:65: free 0xd9d708d0
script/script.c:65: free 0xd9d70570
script/script.c:65: free 0xd9d705a0
script/script.c:65: free 0xd9d705c0
script/script.c:65: free 0xd9d705f0
script/script.c:65: free 0xcba900d0
script/script.c:65: free 0xd9d70620
script/script.c:65: free 0xd9d70650
script/script.c:65: free 0xd9d70670
script/script.c:65: free 0xcba8c4a0
script/script.c:65: free 0xd9d706a0
script/script.c:65: free 0xd9d707d0
script/script.c:65: free 0xd9d70800
script/script.c:65: free 0xd9d70830
script/lexer.c:321: token 259 text [
]
script/script.c:50: malloc 0xd9d707b0
script/script.c:50: malloc 0xcba900d0
script/lexer.c:321: token 0 text []
script/script.c:50: malloc 0xd9d70780
script/script.c:50: malloc 0xcba8c4a0
script/script.c:65: free 0xcba8c4a0
script/script.c:65: free 0xd9d70780
script/script.c:65: free 0xcba900d0
script/script.c:65: free 0xd9d707b0
script/lexer.c:321: token 288 text [set]
script/script.c:50: malloc 0xd9d70770
script/script.c:50: malloc 0xcba8c4a0
script/script.c:163: arglist
script/script.c:50: malloc 0xd9d70740
script/lexer.c:321: token 289 text [root=]
script/script.c:50: malloc 0xd9d705e0
script/script.c:50: malloc 0xcba900d0
script/lexer.c:321: token 289 text [(hd0,msdos1)]
script/script.c:50: malloc 0xd9d705b0
script/script.c:50: malloc 0xd9d70580
script/lexer.c:321: token 289 text []
script/script.c:50: malloc 0xd9d706d0
script/script.c:50: malloc 0xd9d70560
script/script.c:163: arglist
script/script.c:50: malloc 0xd9d70530
script/lexer.c:321: token 259 text [
]
script/script.c:50: malloc 0xd9d70500
script/script.c:50: malloc 0xd9d704e0
script/script.c:198: cmdline
script/script.c:50: malloc 0xd9d704b0
script/lexer.c:321: token 0 text []
script/script.c:50: malloc 0xd9d70810
script/script.c:50: malloc 0xd9d707f0
script/script.c:294: append command
script/script.c:50: malloc 0xd9d70490
script/script.c:65: free 0xd9d70490
script/script.c:65: free 0xd9d707f0
script/script.c:65: free 0xd9d70810
script/script.c:65: free 0xd9d704b0
script/script.c:65: free 0xd9d704e0
script/script.c:65: free 0xd9d70500
script/script.c:65: free 0xd9d70530
script/script.c:65: free 0xd9d70560
script/script.c:65: free 0xd9d706d0
script/script.c:65: free 0xd9d70580
script/script.c:65: free 0xd9d705b0
script/script.c:65: free 0xcba900d0
script/script.c:65: free 0xd9d705e0
script/script.c:65: free 0xd9d70740
script/script.c:65: free 0xcba8c4a0
script/script.c:65: free 0xd9d70770
script/lexer.c:321: token 288 text [multiboot]
script/script.c:50: malloc 0xd9d70750
script/script.c:50: malloc 0xd9d70720
script/script.c:163: arglist
script/script.c:50: malloc 0xd9d706f0
script/lexer.c:321: token 289 text [/boot/kernel]
script/script.c:50: malloc 0xd9d705c0
script/script.c:50: malloc 0xd9d70590
script/script.c:163: arglist
script/script.c:50: malloc 0xd9d70560
script/lexer.c:321: token 259 text [
]
script/script.c:50: malloc 0xd9d70530
script/script.c:50: malloc 0xcba900d0
script/script.c:198: cmdline
script/script.c:50: malloc 0xd9d70500
script/lexer.c:321: token 0 text []
script/script.c:50: malloc 0xd9d707f0
script/script.c:50: malloc 0xcba8c4a0
script/script.c:294: append command
script/script.c:50: malloc 0xd9d707d0
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
fs/fat.c:553: fat_size=32, next_cluster=143
kern/disk.c:295: Closing `hd0'.
kern/dl.c:602: module at 0xcba853b0, size 0x36d8
kern/dl.c:626: relocating to 0xcba8ba10
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
kern/disk.c:295: Closing `hd0'.
kern/dl.c:602: module at 0xcba89f20, size 0x17a4
kern/dl.c:626: relocating to 0xcba8b880
kern/dl.c:556: flushing 0x15c4 bytes at 0xcba83dd0
kern/dl.c:649: module name: video
kern/dl.c:650: init function: 0x0
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
fs/fat.c:553: fat_size=32, next_cluster=160
fs/fat.c:553: fat_size=32, next_cluster=327
fs/fat.c:553: fat_size=32, next_cluster=328
fs/fat.c:553: fat_size=32, next_cluster=329
fs/fat.c:553: fat_size=32, next_cluster=330
fs/fat.c:553: fat_size=32, next_cluster=331
kern/disk.c:295: Closing `hd0'.
kern/dl.c:602: module at 0xd9d31930, size 0xb810
kern/dl.c:626: relocating to 0xcba8b710
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
fs/fat.c:553: fat_size=32, next_cluster=160
kern/disk.c:295: Closing `hd0'.
kern/dl.c:602: module at 0xcba8ad80, size 0x620
kern/dl.c:626: relocating to 0xcba8b5a0
kern/dl.c:556: flushing 0x456 bytes at 0xcba8a910
kern/dl.c:649: module name: priority_queue
kern/dl.c:650: init function: 0x0
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
fs/fat.c:553: fat_size=32, next_cluster=160
fs/fat.c:553: fat_size=32, next_cluster=334
kern/disk.c:295: Closing `hd0'.
kern/dl.c:602: module at 0xcba8a1b0, size 0x4e4
kern/dl.c:626: relocating to 0xcba8b430
kern/dl.c:556: flushing 0x346 bytes at 0xcba8b0b0
kern/dl.c:649: module name: datetime
kern/dl.c:650: init function: 0x0
kern/dl.c:556: flushing 0x105d5 bytes at 0xd9cdb9c0
kern/dl.c:649: module name: net
kern/dl.c:650: init function: 0xd9cdd964
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
fs/fat.c:553: fat_size=32, next_cluster=160
fs/fat.c:553: fat_size=32, next_cluster=288
kern/disk.c:295: Closing `hd0'.
kern/dl.c:602: module at 0xcba73d10, size 0x3a38
kern/dl.c:626: relocating to 0xcba7aea0
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
fs/fat.c:553: fat_size=32, next_cluster=160
fs/fat.c:553: fat_size=32, next_cluster=291
kern/disk.c:295: Closing `hd0'.
kern/dl.c:602: module at 0xcba789e0, size 0x2154
kern/dl.c:626: relocating to 0xcba7ad30
kern/dl.c:556: flushing 0x1f60 bytes at 0xcba599d0
kern/dl.c:649: module name: mmap
kern/dl.c:650: init function: 0xcba5aa24
kern/dl.c:556: flushing 0x37ce bytes at 0xcba558d0
kern/dl.c:649: module name: relocator
kern/dl.c:650: init function: 0x0
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
fs/fat.c:553: fat_size=32, next_cluster=160
fs/fat.c:553: fat_size=32, next_cluster=334
kern/disk.c:295: Closing `hd0'.
kern/dl.c:602: module at 0xcba7a0c0, size 0x8e8
kern/dl.c:626: relocating to 0xcba7aba0
kern/dl.c:556: flushing 0x6fe bytes at 0xcba799b0
kern/dl.c:649: module name: lsapm
kern/dl.c:650: init function: 0xcba79b84
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
fs/fat.c:553: fat_size=32, next_cluster=160
fs/fat.c:553: fat_size=32, next_cluster=334
fs/fat.c:553: fat_size=32, next_cluster=375
kern/disk.c:295: Closing `hd0'.
kern/dl.c:602: module at 0xcba771e0, size 0x2674
kern/dl.c:626: relocating to 0xcba7aa30
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
fs/fat.c:553: fat_size=32, next_cluster=155
fs/fat.c:553: fat_size=32, next_cluster=156
kern/disk.c:295: Closing `hd0'.
kern/dl.c:602: module at 0xd9d38060, size 0x50e0
kern/dl.c:626: relocating to 0xcba7a8a0
kern/dl.c:556: flushing 0x4eec bytes at 0xd9ca7060
kern/dl.c:649: module name: video_fb
kern/dl.c:650: init function: 0x0
kern/dl.c:556: flushing 0x275e bytes at 0xcba744c0
kern/dl.c:649: module name: vbe
kern/dl.c:650: init function: 0xcba75603
kern/dl.c:556: flushing 0x3514 bytes at 0xd9d39c20
kern/dl.c:649: module name: multiboot
kern/dl.c:650: init function: 0xd9d3b50e
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/fs.c:56: Detecting fat...
lib/relocator.c:115: relocators_size=7
fs/fat.c:553: fat_size=32, next_cluster=400
fs/fat.c:553: fat_size=32, next_cluster=401
fs/fat.c:553: fat_size=32, next_cluster=402
lib/relocator.c:1251: min_addr = 0x0, max_addr = 0xffffffff, target = 0x400000
lib/relocator.c:434: trying to allocate in 0x400000-0xffffffff aligned 0x1 size
0x40aae000
lib/relocator.c:1198: allocated: 0x400000+0x40aae000
lib/relocator.c:1287: allocated 0x400000/0x400000
lib/relocator.c:1305: relocators_size=7
lib/relocator.c:1313: relocators_size=7
lib/relocator.c:1320: cur = 0xcba88860, next = 0x0
loader/multiboot.c:127: link_base_addr=0x400000, load_base_addr=0x400000,
load_size=0x40aae000, relocatable=0
loader/multiboot.c:140: segment 0: paddr=0x400000, memsz=0x3d1e5,
vaddr=0x400000
fs/fat.c:553: fat_size=32, next_cluster=400
fs/fat.c:553: fat_size=32, next_cluster=401
fs/fat.c:553: fat_size=32, next_cluster=402
fs/fat.c:553: fat_size=32, next_cluster=403
fs/fat.c:553: fat_size=32, next_cluster=404
fs/fat.c:553: fat_size=32, next_cluster=405
fs/fat.c:553: fat_size=32, next_cluster=406
fs/fat.c:553: fat_size=32, next_cluster=407
fs/fat.c:553: fat_size=32, next_cluster=408
fs/fat.c:553: fat_size=32, next_cluster=409
fs/fat.c:553: fat_size=32, next_cluster=410
fs/fat.c:553: fat_size=32, next_cluster=411
fs/fat.c:553: fat_size=32, next_cluster=412
fs/fat.c:553: fat_size=32, next_cluster=413
fs/fat.c:553: fat_size=32, next_cluster=414
fs/fat.c:553: fat_size=32, next_cluster=415
fs/fat.c:553: fat_size=32, next_cluster=416
fs/fat.c:553: fat_size=32, next_cluster=417
fs/fat.c:553: fat_size=32, next_cluster=418
fs/fat.c:553: fat_size=32, next_cluster=419
fs/fat.c:553: fat_size=32, next_cluster=420
fs/fat.c:553: fat_size=32, next_cluster=421
fs/fat.c:553: fat_size=32, next_cluster=422
fs/fat.c:553: fat_size=32, next_cluster=423
fs/fat.c:553: fat_size=32, next_cluster=424
fs/fat.c:553: fat_size=32, next_cluster=425
fs/fat.c:553: fat_size=32, next_cluster=426
fs/fat.c:553: fat_size=32, next_cluster=427
fs/fat.c:553: fat_size=32, next_cluster=428
fs/fat.c:553: fat_size=32, next_cluster=429
fs/fat.c:553: fat_size=32, next_cluster=430
fs/fat.c:553: fat_size=32, next_cluster=431
fs/fat.c:553: fat_size=32, next_cluster=432
loader/multiboot.c:140: segment 1: paddr=0x43d1f0, memsz=0x3, vaddr=0x43d1f0
loader/multiboot.c:140: segment 2: paddr=0x600000, memsz=0x2bd4,
vaddr=0x600000
# fs/fat.c:553: fat_size=32, next_cluster=0 ... 1024 repeats for about 5000 more lines
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/disk.c:295: Closing `hd0'.
kern/disk.c:196: Opening `hd0,msdos1'...
partmap/msdos.c:188: partition 0: flag 0x80, type 0xef, start 0x800, len
0x1cd125a
kern/disk.c:295: Closing `hd0'.
kern/disk.c:295: Closing `hd0'.
script/script.c:65: free 0xd9d707d0
script/script.c:65: free 0xcba8c4a0
script/script.c:65: free 0xd9d707f0
script/script.c:65: free 0xd9d70500
script/script.c:65: free 0xcba900d0
script/script.c:65: free 0xd9d70530
script/script.c:65: free 0xd9d70560
script/script.c:65: free 0xd9d70590
script/script.c:65: free 0xd9d705c0
script/script.c:65: free 0xd9d706f0
script/script.c:65: free 0xd9d70720
script/script.c:65: free 0xd9d70750
script/lexer.c:321: token 288 text [boot]
script/script.c:50: malloc 0xcba81850
script/script.c:50: malloc 0xcba81830
script/script.c:163: arglist
script/script.c:50: malloc 0xcba81800
script/lexer.c:321: token 259 text [
]
script/script.c:50: malloc 0xcba817d0
script/script.c:50: malloc 0xcba817b0
script/script.c:198: cmdline
script/script.c:50: malloc 0xcba81780
script/lexer.c:321: token 0 text []
script/script.c:50: malloc 0xcba818f0
script/script.c:50: malloc 0xcba81760
script/script.c:294: append command
script/script.c:50: malloc 0xcba81740
lib/relocator.c:1397: chunks = 0xcba79190
lib/relocator.c:434: trying to allocate in 0x10000-0x9b5a4 aligned 0x4 size
0x4a5c
lib/relocator.c:1423: Adjusted limits from 10000-9b5a4 to 0-100000
lib/relocator.c:434: trying to allocate in 0x0-0x100000 aligned 0x4 size
0x4a5c
lib/relocator.c:434: trying to allocate in 0x40eae000-0xffffffff aligned 0x1
size 0x4a5c
lib/relocator.c:1198: allocated: 0xd9d647f4+0x4a5c
lib/relocator.c:1478: relocators_size=7
lib/relocator.c:1486: relocators_size=29
lib/relocator.c:1492: cur = 0xcba88800, next = 0xcba79190
lib/relocator.c:1397: chunks = 0xcba88800
lib/relocator.c:434: trying to allocate in 0x1000-0x99f30 aligned 0x10 size
0xd0
lib/relocator.c:1423: Adjusted limits from 1000-99f30 to 0-100000
lib/relocator.c:434: trying to allocate in 0x0-0x100000 aligned 0x10 size 0xd0
lib/relocator.c:434: trying to allocate in 0x40eae000-0xffffffff aligned 0x1
size 0xd0
lib/relocator.c:1198: allocated: 0xd9d73800+0xd0
lib/relocator.c:1478: relocators_size=29
lib/relocator.c:1486: relocators_size=51
lib/relocator.c:1492: cur = 0xcba81710, next = 0xcba88800
lib/relocator.c:1533: Preparing relocs (size=51)
lib/relocator.c:434: trying to allocate in 0x0-0xffffffcd aligned 0x1 size
0x33
lib/relocator.c:1198: allocated: 0x161056+0x33
lib/relocator.c:1545: Relocs allocated at 0x161056 # This is location it jumps to
lib/relocator.c:1560: chunk 0xd9d73800->0x1000, 0xd0
lib/relocator.c:1560: chunk 0xd9d647f4->0x10000, 0x4a5c
lib/relocator.c:1560: chunk 0x15e57f->0x15e57f, 0x2ad7
lib/relocator.c:1560: chunk 0x15e3dc->0x15e3dc, 0x1a3
lib/relocator.c:1560: chunk 0x10005c->0x10005c, 0x5e380
lib/relocator.c:1560: chunk 0x100028->0x100028, 0x33
lib/relocator.c:1560: chunk 0x100000->0x100000, 0x28
lib/relocator.c:1560: chunk 0x400000->0x400000, 0x40aae000
lib/relocator.c:1604: sorted chunk 0x100000->0x100000, 0x28
lib/relocator.c:1604: sorted chunk 0x100028->0x100028, 0x33
lib/relocator.c:1604: sorted chunk 0x10005c->0x10005c, 0x5e380
lib/relocator.c:1604: sorted chunk 0x15e3dc->0x15e3dc, 0x1a3
lib/relocator.c:1604: sorted chunk 0x15e57f->0x15e57f, 0x2ad7
lib/relocator.c:1604: sorted chunk 0x400000->0x400000, 0x40aae000
lib/relocator.c:1604: sorted chunk 0xd9d647f4->0x10000, 0x4a5c
lib/relocator.c:1604: sorted chunk 0xd9d73800->0x1000, 0xd0
GRUB2 的最后几行位于文件中grub/grub-core/lib/i386/relocator.c和函数grub_relocator32_boot：
// Line 104 - 113
grub_memmove (get_virtual_current_address (ch), &grub_relocator32_start,
RELOCATOR_SIZEOF (32));
err = grub_relocator_prepare_relocs (rel, get_physical_target_address (ch),
&relst, NULL);
if (err)
return err;
asm volatile ("cli");
((void (*) (void)) relst) (); // This last line run, its job is to jump into the kernel
// The value of relst is 0x161056
在此之后，内核永远不会开始运行，GRUB2 的光标永远闪烁并且没有响应（无法输入）。内核的多重引导标头仅指定标志位 1，这意味着它在引导时需要一些内存信息。有人知道为什么会发生这种情况吗？我根据英特尔已知的坏内存区域检查了内存位置，但没有任何结果。我也尝试了命令--quirk的选项multiboot，但都没有帮助。