powerpc/kexec_file: print configured kernel command line

powerpc/kexec_file: print configured kernel command line

[Sourabh Jain]

Kexec with the -d option prints extra logs about the kexec/kdump kernel
that help debug kexec and kdump. For example, it shows what kexec
segments are loaded, their locations, and sizes.

One key piece of information still missing is the kernel command line
configured for the kexec/kdump kernel.

With this patch included, the kernel will print the kernel command line
configured for the kexec/kdump kernel as shown below:

kexec --initrd=./initrd ./kernel -lspd --command-line="test1 test2"

Loaded elf core header at 0x22e30000, bufsz=0x2000 memsz=0x80000
kexec_elf: Command line: elfcorehdr=0x22e30000 test1 test2   <--- New
kexec_elf: Loaded initrd at 0x22eb0000

Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 arch/powerpc/kexec/elf_64.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
index 5d6d616404cf..db0af790c784 100644
--- a/arch/powerpc/kexec/elf_64.c
+++ b/arch/powerpc/kexec/elf_64.c
@@ -90,6 +90,8 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 		cmdline = modified_cmdline;
 	}
 
+	kexec_dprintk("Command line: %s", cmdline ? cmdline : "");
+
 	if (initrd != NULL) {
 		kbuf.buffer = initrd;
 		kbuf.bufsz = kbuf.memsz = initrd_len;
-- 
2.50.1

Re: powerpc/kexec_file: print configured kernel command line

[Ritesh Harjani]

Sourabh Jain <sourabhjain@linux.ibm.com> writes:

> Kexec with the -d option prints extra logs about the kexec/kdump kernel
> that help debug kexec and kdump. For example, it shows what kexec
> segments are loaded, their locations, and sizes.
>
> One key piece of information still missing is the kernel command line
> configured for the kexec/kdump kernel.
>
> With this patch included, the kernel will print the kernel command line
> configured for the kexec/kdump kernel as shown below:
>
> kexec --initrd=./initrd ./kernel -lspd --command-line="test1 test2"
>
> Loaded elf core header at 0x22e30000, bufsz=0x2000 memsz=0x80000
> kexec_elf: Command line: elfcorehdr=0x22e30000 test1 test2   <--- New
> kexec_elf: Loaded initrd at 0x22eb0000
>

Looks like this slipped through the cracks. agreed that this is good to
have info. LGTM. So please feel free to add:

Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>

(this was still cleanly applicable on my latest dev tree)

> Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>

-ritesh

Re: powerpc/kexec_file: print configured kernel command line

[Mukesh Kumar Chaurasiya]

On Fri, Jul 25, 2025 at 06:14:38PM +0530, Sourabh Jain wrote:
> Kexec with the -d option prints extra logs about the kexec/kdump kernel
> that help debug kexec and kdump. For example, it shows what kexec
> segments are loaded, their locations, and sizes.
> 
> One key piece of information still missing is the kernel command line
> configured for the kexec/kdump kernel.
> 
> With this patch included, the kernel will print the kernel command line
> configured for the kexec/kdump kernel as shown below:
> 
> kexec --initrd=./initrd ./kernel -lspd --command-line="test1 test2"
> 
> Loaded elf core header at 0x22e30000, bufsz=0x2000 memsz=0x80000
> kexec_elf: Command line: elfcorehdr=0x22e30000 test1 test2   <--- New
> kexec_elf: Loaded initrd at 0x22eb0000
> 
> Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
> ---
>  arch/powerpc/kexec/elf_64.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c
> index 5d6d616404cf..db0af790c784 100644
> --- a/arch/powerpc/kexec/elf_64.c
> +++ b/arch/powerpc/kexec/elf_64.c
> @@ -90,6 +90,8 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
>  		cmdline = modified_cmdline;
>  	}
>  
> +	kexec_dprintk("Command line: %s", cmdline ? cmdline : "");
> +
>  	if (initrd != NULL) {
>  		kbuf.buffer = initrd;
>  		kbuf.bufsz = kbuf.memsz = initrd_len;
> -- 
> 2.50.1
> 
> 
Tested this on P11 LPAR.

[  485.755942] kexec_file: kernel: 00000000cb90aae7 kernel_size: 0x1d1531d0
[  485.762870] kexec_elf: Loaded the kernel at 0x80000000
[  485.762930] kexec_elf: Loaded purgatory at 0x9fff0000
[  485.762944] Loaded the backup region at 0x84160000
[  485.763088] crash_core: Crash PT_LOAD ELF header. phdr=00000000364832a7 vaddr=0xc000000000000000, paddr=0x0, sz=0x10000 e_phnum=178 p_offset=0x0
[  485.763095] crash_core: Crash PT_LOAD ELF header. phdr=000000009122d5f0 vaddr=0xc000000000010000, paddr=0x10000, sz=0x7fff0000 e_phnum=179 p_offset=0x10000
[  485.763099] crash_core: Crash PT_LOAD ELF header. phdr=000000007ead431b vaddr=0xc0000000a0000000, paddr=0xa0000000, sz=0xb10000000 e_phnum=180 p_offset=0xa0000000
[  485.763103] crash_core: Crash PT_LOAD ELF header. phdr=0000000001ee8e6f vaddr=0xc000000bb0000000, paddr=0xbb0000000, sz=0x5d0000000 e_phnum=181 p_offset=0xbb0000000
[  485.763108] crash_core: Crash PT_LOAD ELF header. phdr=000000004566b315 vaddr=0xc000001180000000, paddr=0x1180000000, sz=0x1d20000000 e_phnum=182 p_offset=0x1180000000
[  485.763112] crash_core: Crash PT_LOAD ELF header. phdr=00000000a9df7c03 vaddr=0xc000002ea0000000, paddr=0x2ea0000000, sz=0x1d10000000 e_phnum=183 p_offset=0x2ea0000000
[  485.763116] crash_core: Crash PT_LOAD ELF header. phdr=0000000077ee5d4c vaddr=0xc000004bb0000000, paddr=0x4bb0000000, sz=0x1d10000000 e_phnum=184 p_offset=0x4bb0000000
[  485.763119] crash_core: Crash PT_LOAD ELF header. phdr=000000000ea82932 vaddr=0xc0000068c0000000, paddr=0x68c0000000, sz=0x1740000000 e_phnum=185 p_offset=0x68c0000000
[  485.763124] Backup region offset updated to 0x84160000
[  485.763130] Loaded elf core header at 0x84170000, bufsz=0x3000 memsz=0x80000
[  485.763134] No dm-crypt keys
[  485.763139] kexec_elf: Command line: elfcorehdr=0x84170000 BOOT_IMAGE=(ieee1275//vdevice/v-scsi@30000065/disk@8100000000000000,gpt2)/vmlinuz-6.19.7-200.fc43.ppc64le root=/dev/mapper/fedora-root ro rd.lvm.lv=fedora/root crashkernel=512M@2G test1 test2
[  485.763145] kexec_elf: Loaded initrd at 0x841f0000
[  485.763678] Memory node path: /memory@0
[  485.795492] kexec_elf: Loaded device tree at 0x9ffd0000
[  486.417820] kexec_file: nr_segments = 6
[  486.417839] kexec_file: segment[0]: buf=0x00000000ac04377b bufsz=0x3f74bc4 mem=0x80000000 memsz=0x4160000
[  486.424367] kexec_file: segment[1]: buf=0x00000000b22938ec bufsz=0x310 mem=0x9fff0000 memsz=0x10000
[  486.424403] kexec_file: segment[2]: buf=0x0000000043b34bd4 bufsz=0x10000 mem=0x84160000 memsz=0x10000
[  486.424417] kexec_file: segment[3]: buf=0x00000000421e955d bufsz=0x3000 mem=0x84170000 memsz=0x80000
[  486.424450] kexec_file: segment[4]: buf=0x000000009a7ce2c9 bufsz=0x4ed96f8 mem=0x841f0000 memsz=0x4ee0000
[  486.432514] kexec_file: segment[5]: buf=0x0000000023a3b280 bufsz=0x1553b mem=0x9ffd0000 memsz=0x20000
[  486.432558] kexec_file: kexec_file_load: type:1, start:0x9fff0000 head:0x4 flags:0xa


Tested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>