Hello list, I just stumbled over whats looks like a regression in `kexec -l <kernel>` that was introduced in release v2.0.27. I'm using kexec on amd64 in an initrd context and made a bigger jump from v2.0.20 to v2.0.30. After that kexec failed with:
```
$ kexec -l /path/to/kernel
Could not find a free area of memory of 0x9000 bytes...
locate_hole failed
```
I can also reproduce the error on my regulaer desktop system, however, so it
is not specific to the initrd scenario.
I digged a bit deeper and found that the regression was introduced via commit
29fe5067ed07, which implies the `-a` / `--kexec-syscall-auto` option. In the
debugger I see that `info->memory_ranges` is 0 and `get_memory_ranges()` was
never called when `locate_hole()` is executed. When running `kexec -c -l
/path/to/kernel` then everything works as before.
Here is a `gdb` backtrace from the spot where the error pops up:
Breakpoint 2, locate_hole (info=0x7fffffffd690, hole_size=36864,
hole_align=4096, hole_min=12288,
hole_max=655360, hole_end=-1) at kexec/kexec.c:314
314 fprintf(stderr, "Could not find a free area of
memory of "
(gdb) p *info
$2 = {segment = 0x0, nr_segments = 0, memory_range = 0x0, memory_ranges =
0, crash_range = 0x0,
nr_crash_ranges = 0, entry = 0x0, rhdr = {ei_class = 2, ei_data = 1,
e_type = 1, e_machine = 62, e_version = 1,
e_flags = 0, e_phnum = 0, e_shnum = 17, e_shstrndx = 16, e_entry =
1872, e_phoff = 0, e_shoff = 35104,
e_notenum = 1, e_phdr = 0x0, e_shdr = 0x55555566b5d0, e_note =
0x55555566baa0, rel_addr = 0, rel_size = 0},
backup_start = 0, kexec_flags = 0, backup_src_start = 0, backup_src_size
= 0, file_mode = 1, kernel_fd = -1,
initrd_fd = -1, command_line = 0x0, command_line_len = 0, skip_checks =
0, elfcorehdr = 0}
(gdb) bt
#0 locate_hole (info=0x7fffffffd690, hole_size=36864, hole_align=4096,
hole_min=12288, hole_max=655360,
hole_end=-1) at kexec/kexec.c:314
#1 0x000055555555bdaa in add_buffer_phys_virt (info=0x7fffffffd690,
buf=0x55555566c640, bufsz=28896,
memsz=36864, buf_align=4096, buf_min=12288, buf_max=655360, buf_end=-1,
phys=0) at kexec/kexec.c:396
#2 0x000055555555be46 in add_buffer_virt (info=0x7fffffffd690,
buf=0x55555566c640, bufsz=28896, memsz=36864,
buf_align=4096, buf_min=12288, buf_max=655360, buf_end=-1) at
kexec/kexec.c:410
#3 0x000055555556796c in add_buffer (info=0x7fffffffd690,
buf=0x55555566c640, bufsz=28896, memsz=36864,
buf_align=4096, buf_min=12288, buf_max=655360, buf_end=-1) at
kexec/add_buffer.c:12
#4 0x0000555555562243 in elf_rel_load (ehdr=0x7fffffffd6c8,
info=0x7fffffffd690, min=12288, max=655360, end=-1)
at kexec/kexec-elf-rel.c:259
#5 0x0000555555562a91 in elf_rel_build_load (info=0x7fffffffd690,
ehdr=0x7fffffffd6c8,
buf=0x555555580a40 <purgatory> "\177ELF\002\001\001", len=36192,
min=12288, max=655360, end=-1, flags=0)
at kexec/kexec-elf-rel.c:436
#6 0x000055555556894c in do_bzImage_load (info=0x7fffffffd690,
kernel=0x7ffff7464010 '\377' <repeats 200 times>...,
kernel_len=8655872, command_line=0x55555566b5b0 "",
command_line_len=1, initrd=0x0, initrd_len=0, dtb=0x0, dtb_len=0,
real_mode_entry=0)
at kexec/arch/i386/kexec-bzImage.c:211
#7 0x00005555555694ec in bzImage_load (argc=3, argv=0x7fffffffd958,
buf=0x7ffff7464010 '\377' <repeats 200 times>..., len=8655872,
info=0x7fffffffd690)
at kexec/arch/i386/kexec-bzImage.c:467
#8 0x000055555555e269 in do_kexec_file_load (fileind=2, argc=3,
argv=0x7fffffffd958, flags=0)
at kexec/kexec.c:1367
#9 0x000055555555ed65 in main (argc=3, argv=0x7fffffffd958) at
kexec/kexec.c:1758
I'm not sure how the collection of the memory ranges is supposed to work in
this context. The kernel I'm running does have CONFIG_KEXEC_FILE=y set in any
case. I'm also not seeing any relevant failed system calls until the error is
hit.
Regards
Matthias
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