"%#" format specifier automatically adds the "0x" prefix and has one less
character than "0x%".

For conciseness, replace "0x%" with "%#" when printing hexadecimal values
in SEAMCALL error messages.

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Chao Gao <chao.gao@intel.com>
---
"0x%" is also used to print TDMR ranges. I didn't convert them to reduce
code churn, but if they should be converted for consistency, I'm happy
to do that.

v2: new
---
 arch/x86/virt/vmx/tdx/tdx.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
index dbc7cb08ca53..2218bb42af40 100644
--- a/arch/x86/virt/vmx/tdx/tdx.c
+++ b/arch/x86/virt/vmx/tdx/tdx.c
@@ -63,16 +63,16 @@ typedef void (*sc_err_func_t)(u64 fn, u64 err, struct tdx_module_args *args);
 
 static inline void seamcall_err(u64 fn, u64 err, struct tdx_module_args *args)
 {
-	pr_err("SEAMCALL (%llu) failed: 0x%016llx\n", fn, err);
+	pr_err("SEAMCALL (%llu) failed: %#016llx\n", fn, err);
 }
 
 static inline void seamcall_err_ret(u64 fn, u64 err,
 				    struct tdx_module_args *args)
 {
 	seamcall_err(fn, err, args);
-	pr_err("RCX 0x%016llx RDX 0x%016llx R08 0x%016llx\n",
+	pr_err("RCX %#016llx RDX %#016llx R08 %#016llx\n",
 			args->rcx, args->rdx, args->r8);
-	pr_err("R09 0x%016llx R10 0x%016llx R11 0x%016llx\n",
+	pr_err("R09 %#016llx R10 %#016llx R11 %#016llx\n",
 			args->r9, args->r10, args->r11);
 }
 
-- 
2.47.3

On 1/23/26 06:55, Chao Gao wrote:
> "%#" format specifier automatically adds the "0x" prefix and has one less
> character than "0x%".

IMNHO, this is needless bikeshedding about existing code. It's only
function is going to be to distract reviewers from the parts of the set
that actually need review.

If this matters (it doesn't), send it as a separate patch, please.

On 1/23/2026 10:55 PM, Chao Gao wrote:
> "%#" format specifier automatically adds the "0x" prefix and has one less
> character than "0x%".
> 
> For conciseness, replace "0x%" with "%#" when printing hexadecimal values
> in SEAMCALL error messages.
> 
> Suggested-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Chao Gao <chao.gao@intel.com>

Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>

> ---
> "0x%" is also used to print TDMR ranges. I didn't convert them to reduce
> code churn, but if they should be converted for consistency, I'm happy
> to do that.

Generally, is there any preference for coding in Linux kernel about
"0x%" VS. "%#"? Or developers just make their own choices?


> 
> v2: new
> ---
>  arch/x86/virt/vmx/tdx/tdx.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index dbc7cb08ca53..2218bb42af40 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -63,16 +63,16 @@ typedef void (*sc_err_func_t)(u64 fn, u64 err, struct tdx_module_args *args);
>  
>  static inline void seamcall_err(u64 fn, u64 err, struct tdx_module_args *args)
>  {
> -	pr_err("SEAMCALL (%llu) failed: 0x%016llx\n", fn, err);
> +	pr_err("SEAMCALL (%llu) failed: %#016llx\n", fn, err);
>  }
>  
>  static inline void seamcall_err_ret(u64 fn, u64 err,
>  				    struct tdx_module_args *args)
>  {
>  	seamcall_err(fn, err, args);
> -	pr_err("RCX 0x%016llx RDX 0x%016llx R08 0x%016llx\n",
> +	pr_err("RCX %#016llx RDX %#016llx R08 %#016llx\n",
>  			args->rcx, args->rdx, args->r8);
> -	pr_err("R09 0x%016llx R10 0x%016llx R11 0x%016llx\n",
> +	pr_err("R09 %#016llx R10 %#016llx R11 %#016llx\n",
>  			args->r9, args->r10, args->r11);
>  }
>

On Wed, Jan 28, 2026 at 09:34:03AM +0800, Binbin Wu wrote:
>
>
>On 1/23/2026 10:55 PM, Chao Gao wrote:
>> "%#" format specifier automatically adds the "0x" prefix and has one less
>> character than "0x%".
>> 
>> For conciseness, replace "0x%" with "%#" when printing hexadecimal values
>> in SEAMCALL error messages.
>> 
>> Suggested-by: Dan Williams <dan.j.williams@intel.com>
>> Signed-off-by: Chao Gao <chao.gao@intel.com>
>
>Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
>
>> ---
>> "0x%" is also used to print TDMR ranges. I didn't convert them to reduce
>> code churn, but if they should be converted for consistency, I'm happy
>> to do that.
>
>Generally, is there any preference for coding in Linux kernel about
>"0x%" VS. "%#"? Or developers just make their own choices?

There seems to be no clear guidance on "0x%x" vs. "%#x".

If anyone has strong objections to this change, I can definitely drop it. I
included this patch because Dan suggested it during his review, though I'm not
sure how strongly he feels about it.

I searched lore and found the example below where "%#x" is preferred in another
subsystem:

https://lore.kernel.org/all/20251202231352.GF1712166@ZenIV/

On Fri, Jan 23, 2026 at 06:55:10AM -0800, Chao Gao wrote:
> "%#" format specifier automatically adds the "0x" prefix and has one less
> character than "0x%".
> 
> For conciseness, replace "0x%" with "%#" when printing hexadecimal values
> in SEAMCALL error messages.

Reviewed-by: Tony Lindgren <tony.lindgren@linux.intel.com>