在 2025/12/4 20:18, Sourabh Jain 写道:
Hello All,
I read this patch series, including the older versions, and this is
what I
think about the changes.
There are two main reasons I see for why this patch series is proposed
(these were not mentioned in the cover letter or commit messages):
1. Commit eb7622d908a09 ("kexec_file, riscv: print out debugging message
if required") and commit 6f8c1da071a4 ("kexec_file, arm64: print out
debugging message if required") moved some kexec-related debug
prints to
kexec_dprintk instead of pr_debug or pr_notice.
These commits made it easier to control the updated debug prints using
the -d option of kexec tool for kexec_file_load system call. But since
kexec_dprintk is not available for the kexec_load system call,
those prints
are no longer available for kexec_load at all. So patch series try
to bring
those logs for kexec_load system call.
2. Patch 03/03 prints additional logs about the kexec image type, start,
head, and flags via kexec_dprintk for the kexec_load system call.
This is done by enabling the kexec_dprintk for kexec_load, so that logs
from point 1 and the new logs from point 2 can be printed for kexec_load
system call.
However, the patch series does not explain why these additional debug
logs
are needed for kexec_load. Since most of the work involved in loading
kexec images through kexec_load happens in the kexec userspace tool, and
the tool already provides enough logs to debug issues, the need for these
extra kernel logs is not clear.
As pointed out in the point 1, these two commits not only move some
kexec-related debug prints to kexec_dprintk instead of pr_debug or
pr_notice,
but also respectively remove and delete the debug print in kexec_image_info.
These debug print initially existed for both kexec_load and
kexec_file_load in kernel space.
Just commit cbc2fe9d9cb2 ("kexec_file: The "add kexec_file flag to
control debug printing")
series of patches removed or deleted some parts, but this series of
patches only added them
to the generic code under the kexec_file_load path, not to the
kexec_load path.
Therefore, the reason for adding this part of the debug print is to add
this deleted debug print
to the kexec_load generic code. Regarding duplicate prints related to
architecture, as mentioned
in previous posts[1], I want remove the print(type/head of kimage) in
arm64, and then add it
to the general code.
[1]:
https://lore.kernel.org/lkml/4d709a5e16be5dec+04521049-61de-411f-85c1-cfc049ff0...@uniontech.com/
If commit cbc2fe9d9cb2 ("kexec_file: The "add kexec_file flag to control
debug printing" series of patches
is indeed intended to remove those kexec_image_info in kexec_load, not
to lose them.
I think patch 3 can be removed, but patch 1, 2 are still required.
As Sourabh Jain mentioned in the point 1, the debugging print that uses
kexec_dprintk
in the kexec_load path currently existing under arm64 is equivalent to
being unavailable.
So adding the need for the additional debug logs in the cover letter or
commit message is needed to decide whether it is worth adding the code
change proposed in this patch series Also, I found it hard to map the
commit message to the changes introduced in the commits. And finally
If I review the patches only based on the code changes: 01/03 The
commit message refers to kexec_dbg_print
There is an error in the patch description. It should be
kexec_file_dbg_print. I will fix it.
as kexec_core_dbg_print. 02/03 I think kexec_dbg_print should be set
to false at the end of kimage_free, not at the start. 03/03 There is
duplication of debug logs for architectures that already print the
same information. For example, arm64. -
In the kimage_file_alloc_init()/kimage_alloc_init(), if there is an
abnormal exit before executing *rimage = image,
the image is empty, but kexec_dbg_print has been initialized.
In this case, It needs to be placed at the beginning of kimage_free to
reset it.
Sourabh Jain
On 26/11/25 14:14, Qiang Ma wrote:
Overview:
=========
The commit a85ee18c7900 ("kexec_file: print out debugging message
if required") has added general code printing in kexec_file_load(),
but not in kexec_load().
Since kexec_load and kexec_file_load are not triggered
simultaneously,
we can unify the debug flag of kexec and kexec_file as kexec_dbg_print.
Next, we need to do some things in this patchset:
1. rename kexec_file_dbg_print to kexec_dbg_print
2. Add KEXEC_DEBUG
3. Initialize kexec_dbg_print for kexec
4. Fix uninitialized struct kimage *image pointer
5. Set the reset of kexec_dbg_print to kimage_free
Testing:
=========
I did testing on x86_64, arm64 and loongarch. On x86_64, the printed
messages
look like below:
unset CONFIG_KEXEC_FILE:
[ 81.502374] kexec: kexec_load: type:0, start:0x23fff7700
head:0x10a4b9002 flags:0x3e0010
set CONFIG_KEXEC_FILE
[ 36.774228] kexec_file: kernel: 0000000066c386c8 kernel_size:
0xd78400
[ 36.821814] kexec-bzImage64: Loaded purgatory at 0x23fffb000
[ 36.821826] kexec-bzImage64: Loaded boot_param, command line and
misc at 0x23fff9000 bufsz=0x12d0 memsz=0x2000
[ 36.821829] kexec-bzImage64: Loaded 64bit kernel at 0x23d400000
bufsz=0xd73400 memsz=0x2ab7000
[ 36.821918] kexec-bzImage64: Loaded initrd at 0x23bd0b000
bufsz=0x16f40a8 memsz=0x16f40a8
[ 36.821920] kexec-bzImage64: Final command line is:
root=/dev/mapper/test-root crashkernel=auto rd.lvm.lv=test/root
[ 36.821925] kexec-bzImage64: E820 memmap:
[ 36.821926] kexec-bzImage64: 0000000000000000-000000000009ffff (1)
[ 36.821928] kexec-bzImage64: 0000000000100000-0000000000811fff (1)
[ 36.821930] kexec-bzImage64: 0000000000812000-0000000000812fff (2)
[ 36.821931] kexec-bzImage64: 0000000000813000-00000000bee38fff (1)
[ 36.821933] kexec-bzImage64: 00000000bee39000-00000000beec2fff (2)
[ 36.821934] kexec-bzImage64: 00000000beec3000-00000000bf8ecfff (1)
[ 36.821935] kexec-bzImage64: 00000000bf8ed000-00000000bfb6cfff (2)
[ 36.821936] kexec-bzImage64: 00000000bfb6d000-00000000bfb7efff (3)
[ 36.821937] kexec-bzImage64: 00000000bfb7f000-00000000bfbfefff (4)
[ 36.821938] kexec-bzImage64: 00000000bfbff000-00000000bff7bfff (1)
[ 36.821939] kexec-bzImage64: 00000000bff7c000-00000000bfffffff (2)
[ 36.821940] kexec-bzImage64: 00000000feffc000-00000000feffffff (2)
[ 36.821941] kexec-bzImage64: 00000000ffc00000-00000000ffffffff (2)
[ 36.821942] kexec-bzImage64: 0000000100000000-000000023fffffff (1)
[ 36.872348] kexec_file: nr_segments = 4
[ 36.872356] kexec_file: segment[0]: buf=0x000000005314ece7
bufsz=0x4000 mem=0x23fffb000 memsz=0x5000
[ 36.872370] kexec_file: segment[1]: buf=0x000000006e59b143
bufsz=0x12d0 mem=0x23fff9000 memsz=0x2000
[ 36.872374] kexec_file: segment[2]: buf=0x00000000eb7b1fc3
bufsz=0xd73400 mem=0x23d400000 memsz=0x2ab7000
[ 36.882172] kexec_file: segment[3]: buf=0x000000006af76441
bufsz=0x16f40a8 mem=0x23bd0b000 memsz=0x16f5000
[ 36.889113] kexec_file: kexec_file_load: type:0, start:0x23fffb150
head:0x101a2e002 flags:0x8
Changes in v3:
==========
- Rename kexec_core_dbg_print to kexec_dbg_print
- Remove unnecessary segments prints
- Remove patch "kexec_file: Fix the issue of mismatch between loop
variable types"
Qiang Ma (3):
kexec: Fix uninitialized struct kimage *image pointer
kexec: add kexec flag to control debug printing
kexec: print out debugging message if required for kexec_load
include/linux/kexec.h | 9 +++++----
include/uapi/linux/kexec.h | 1 +
kernel/kexec.c | 8 +++++++-
kernel/kexec_core.c | 4 +++-
kernel/kexec_file.c | 4 +---
5 files changed, 17 insertions(+), 9 deletions(-)
