[PATCH] LoongArch: Change COMMAND_LINE_SIZE to 4096

[PATCH] LoongArch: Change COMMAND_LINE_SIZE to 4096

[Chenghao Duan]

The default COMMAND_LINE_SIZE inherited from asm-generic is 512, which
is too small for modern use cases. For example, when the parameter path
in the cmdline of the kdump first kernel is too long, the limit is
easily exceeded when loading the second kernel.

Increase the command line size to 4096 bytes, In LoongArch, this is
consistent with the upstream configuration of the Linux kernel.
linux kernel commit: f7794a4d92ade518c813de69a01b27ca6d8d86f3.

This patch is necessary because the Linux kernel has been changed to
4096. When the kernel cmdline size exceeds 512, the --reuse-cmdline
option of the kexec command will inevitably result in an error.

The COMMAND_LINE_SIZE in kexec/arch/loongarch/crashdump-loongarch.h
is unused, so it is removed here.

Suggested-by: Youling Tang <tangyouling@kylinos.cn>
Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
---
 kexec/arch/loongarch/crashdump-loongarch.h | 2 --
 kexec/arch/loongarch/kexec-loongarch.h     | 2 +-
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/kexec/arch/loongarch/crashdump-loongarch.h b/kexec/arch/loongarch/crashdump-loongarch.h
index 25ff24b..dac9e71 100644
--- a/kexec/arch/loongarch/crashdump-loongarch.h
+++ b/kexec/arch/loongarch/crashdump-loongarch.h
@@ -20,7 +20,5 @@ int get_crash_kernel_load_range(uint64_t *start, uint64_t *end);
 /* crash dump kernel support at most two regions, low_region and high region. */
 #define CRASH_MAX_RESERVED_RANGES      2
 
-#define COMMAND_LINE_SIZE	512
-
 extern struct arch_options_t arch_options;
 #endif /* CRASHDUMP_LOONGARCH_H */
diff --git a/kexec/arch/loongarch/kexec-loongarch.h b/kexec/arch/loongarch/kexec-loongarch.h
index 2c7624f..0bd462f 100644
--- a/kexec/arch/loongarch/kexec-loongarch.h
+++ b/kexec/arch/loongarch/kexec-loongarch.h
@@ -13,7 +13,7 @@
 
 #define CORE_TYPE_ELF64 1
 
-#define COMMAND_LINE_SIZE 512
+#define COMMAND_LINE_SIZE 4096
 
 #define KiB(x) ((x) * 1024UL)
 #define MiB(x) (KiB(x) * 1024UL)
-- 
2.25.1

Re: [PATCH] LoongArch: Change COMMAND_LINE_SIZE to 4096

[Chenghao Duan]

On Mon, Sep 22, 2025 at 10:10:57AM +0800, Chenghao Duan wrote:
> The default COMMAND_LINE_SIZE inherited from asm-generic is 512, which
> is too small for modern use cases. For example, when the parameter path
> in the cmdline of the kdump first kernel is too long, the limit is
> easily exceeded when loading the second kernel.
> 
> Increase the command line size to 4096 bytes, In LoongArch, this is
> consistent with the upstream configuration of the Linux kernel.
> linux kernel commit: f7794a4d92ade518c813de69a01b27ca6d8d86f3.

linux kernel commit: f7794a4d92a(LoongArch: Increase COMMAND_LINE_SIZE up to 4096)

> 
> This patch is necessary because the Linux kernel has been changed to
> 4096. When the kernel cmdline size exceeds 512, the --reuse-cmdline
> option of the kexec command will inevitably result in an error.
> 
> The COMMAND_LINE_SIZE in kexec/arch/loongarch/crashdump-loongarch.h
> is unused, so it is removed here.
> 
> Suggested-by: Youling Tang <tangyouling@kylinos.cn>
> Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
> ---
>  kexec/arch/loongarch/crashdump-loongarch.h | 2 --
>  kexec/arch/loongarch/kexec-loongarch.h     | 2 +-
>  2 files changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/kexec/arch/loongarch/crashdump-loongarch.h b/kexec/arch/loongarch/crashdump-loongarch.h
> index 25ff24b..dac9e71 100644
> --- a/kexec/arch/loongarch/crashdump-loongarch.h
> +++ b/kexec/arch/loongarch/crashdump-loongarch.h
> @@ -20,7 +20,5 @@ int get_crash_kernel_load_range(uint64_t *start, uint64_t *end);
>  /* crash dump kernel support at most two regions, low_region and high region. */
>  #define CRASH_MAX_RESERVED_RANGES      2
>  
> -#define COMMAND_LINE_SIZE	512
> -
>  extern struct arch_options_t arch_options;
>  #endif /* CRASHDUMP_LOONGARCH_H */
> diff --git a/kexec/arch/loongarch/kexec-loongarch.h b/kexec/arch/loongarch/kexec-loongarch.h
> index 2c7624f..0bd462f 100644
> --- a/kexec/arch/loongarch/kexec-loongarch.h
> +++ b/kexec/arch/loongarch/kexec-loongarch.h
> @@ -13,7 +13,7 @@
>  
>  #define CORE_TYPE_ELF64 1
>  
> -#define COMMAND_LINE_SIZE 512
> +#define COMMAND_LINE_SIZE 4096
>  
>  #define KiB(x) ((x) * 1024UL)
>  #define MiB(x) (KiB(x) * 1024UL)
> -- 
> 2.25.1

Re: [PATCH] LoongArch: Change COMMAND_LINE_SIZE to 4096

[Chenghao Duan]

On Mon, Sep 22, 2025 at 10:10:57AM +0800, Chenghao Duan wrote:
> The default COMMAND_LINE_SIZE inherited from asm-generic is 512, which
> is too small for modern use cases. For example, when the parameter path
> in the cmdline of the kdump first kernel is too long, the limit is
> easily exceeded when loading the second kernel.
> 
> Increase the command line size to 4096 bytes, In LoongArch, this is
> consistent with the upstream configuration of the Linux kernel.
> linux kernel commit: f7794a4d92ade518c813de69a01b27ca6d8d86f3.

I'm very sorry, but the commit ID in the previous email was incorrect.
linux kernel commit: f7794a4d92ad(LoongArch: Increase COMMAND_LINE_SIZE up to 4096).

> 
> This patch is necessary because the Linux kernel has been changed to
> 4096. When the kernel cmdline size exceeds 512, the --reuse-cmdline
> option of the kexec command will inevitably result in an error.
> 
> The COMMAND_LINE_SIZE in kexec/arch/loongarch/crashdump-loongarch.h
> is unused, so it is removed here.
> 
> Suggested-by: Youling Tang <tangyouling@kylinos.cn>
> Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
> ---
>  kexec/arch/loongarch/crashdump-loongarch.h | 2 --
>  kexec/arch/loongarch/kexec-loongarch.h     | 2 +-
>  2 files changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/kexec/arch/loongarch/crashdump-loongarch.h b/kexec/arch/loongarch/crashdump-loongarch.h
> index 25ff24b..dac9e71 100644
> --- a/kexec/arch/loongarch/crashdump-loongarch.h
> +++ b/kexec/arch/loongarch/crashdump-loongarch.h
> @@ -20,7 +20,5 @@ int get_crash_kernel_load_range(uint64_t *start, uint64_t *end);
>  /* crash dump kernel support at most two regions, low_region and high region. */
>  #define CRASH_MAX_RESERVED_RANGES      2
>  
> -#define COMMAND_LINE_SIZE	512
> -
>  extern struct arch_options_t arch_options;
>  #endif /* CRASHDUMP_LOONGARCH_H */
> diff --git a/kexec/arch/loongarch/kexec-loongarch.h b/kexec/arch/loongarch/kexec-loongarch.h
> index 2c7624f..0bd462f 100644
> --- a/kexec/arch/loongarch/kexec-loongarch.h
> +++ b/kexec/arch/loongarch/kexec-loongarch.h
> @@ -13,7 +13,7 @@
>  
>  #define CORE_TYPE_ELF64 1
>  
> -#define COMMAND_LINE_SIZE 512
> +#define COMMAND_LINE_SIZE 4096
>  
>  #define KiB(x) ((x) * 1024UL)
>  #define MiB(x) (KiB(x) * 1024UL)
> -- 
> 2.25.1

Re: [PATCH] LoongArch: Change COMMAND_LINE_SIZE to 4096

[Simon Horman]

On Mon, Sep 22, 2025 at 10:58:21AM +0800, Chenghao Duan wrote:
> On Mon, Sep 22, 2025 at 10:10:57AM +0800, Chenghao Duan wrote:
> > The default COMMAND_LINE_SIZE inherited from asm-generic is 512, which
> > is too small for modern use cases. For example, when the parameter path
> > in the cmdline of the kdump first kernel is too long, the limit is
> > easily exceeded when loading the second kernel.
> > 
> > Increase the command line size to 4096 bytes, In LoongArch, this is
> > consistent with the upstream configuration of the Linux kernel.
> > linux kernel commit: f7794a4d92ade518c813de69a01b27ca6d8d86f3.
> 
> I'm very sorry, but the commit ID in the previous email was incorrect.
> linux kernel commit: f7794a4d92ad(LoongArch: Increase COMMAND_LINE_SIZE up to 4096).

Thanks, I have applied this patch.

- LoongArch: Change COMMAND_LINE_SIZE to 4096
  https://git.kernel.org/pub/scm/utils/kernel/kexec/kexec-tools.git/commit/?id=b8f6c2a98d2c

And I updated the text when applying to read:

  Increase the command line size to 4096 bytes, In LoongArch, this is
  consistent with the upstream configuration of the Linux kernel as of
  commit f7794a4d92ad ("LoongArch: Increase COMMAND_LINE_SIZE up to 4096").

> > This patch is necessary because the Linux kernel has been changed to
> > 4096. When the kernel cmdline size exceeds 512, the --reuse-cmdline
> > option of the kexec command will inevitably result in an error.
> > 
> > The COMMAND_LINE_SIZE in kexec/arch/loongarch/crashdump-loongarch.h
> > is unused, so it is removed here.
> > 
> > Suggested-by: Youling Tang <tangyouling@kylinos.cn>
> > Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>

...