[PATCH] x86/realmode: Use const and u32 for embedded real-mode data

[PATCH] x86/realmode: Use const and u32 for embedded real-mode data

[Thorsten Blum]

Declare the embedded real-mode blob and relocation table as const since
they are not modified.

Also declare the relocation table as a u32 array since it contains
32-bit entries, and remove the cast in setup_real_mode().

No functional change.

Signed-off-by: Thorsten Blum <blum@kernel.org>
---
 arch/x86/include/asm/realmode.h | 6 +++---
 arch/x86/realmode/init.c        | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h
index e406a1e92c63..e48259f2e503 100644
--- a/arch/x86/include/asm/realmode.h
+++ b/arch/x86/include/asm/realmode.h
@@ -57,7 +57,7 @@ struct trampoline_header {
 };
 
 extern struct real_mode_header *real_mode_header;
-extern unsigned char real_mode_blob_end[];
+extern const unsigned char real_mode_blob_end[];
 
 extern unsigned long initial_code;
 extern unsigned long initial_stack;
@@ -67,8 +67,8 @@ extern unsigned long initial_vc_handler;
 
 extern u32 *trampoline_lock;
 
-extern unsigned char real_mode_blob[];
-extern unsigned char real_mode_relocs[];
+extern const unsigned char real_mode_blob[];
+extern const u32 real_mode_relocs[];
 
 #ifdef CONFIG_X86_32
 extern unsigned char startup_32_smp[];
diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index 65110b2ee1a1..5430314d549d 100644
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -118,7 +118,7 @@ static void __init setup_real_mode(void)
 	phys_base = __pa(base);
 	real_mode_seg = phys_base >> 4;
 
-	rel = (u32 *) real_mode_relocs;
+	rel = real_mode_relocs;
 
 	/* 16-bit segment relocations. */
 	count = *rel++;

Re: [PATCH] x86/realmode: Use const and u32 for embedded real-mode data

[H. Peter Anvin]

On 2026-11-05 10:10, Thorsten Blum wrote:
> Declare the embedded real-mode blob and relocation table as const since
> they are not modified.
> 
> Also declare the relocation table as a u32 array since it contains
> 32-bit entries, and remove the cast in setup_real_mode().
> 
> No functional change.
> 
> Signed-off-by: Thorsten Blum <blum@kernel.org>
Reviewed-by: H. Peter Anvin (RosaicLabs) <hpa@zytor.com>