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x86/bootflag: Micro-optimize sbf_write()

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Change parity bit with XOR when !parity instead of masking bit out
and conditionally setting it when !parity.

Saves a couple of bytes in the object file.

Co-developed-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250226153709.6370-1-ubizjak@gmail.com
This commit is contained in:
Uros Bizjak
2025-02-26 16:36:56 +01:00
committed by Ingo Molnar
parent 7d8f03f7dd
commit adf6819278
1 changed files with 1 additions and 2 deletions
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3
arch/x86/kernel/bootflag.c
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@@ -38,9 +38,8 @@ static void __init sbf_write(u8 v)
unsigned long flags;
if (sbf_port != -1) {
v &= ~SBF_PARITY;
if (!parity(v))
v |= SBF_PARITY;
v ^= SBF_PARITY;
printk(KERN_INFO "Simple Boot Flag at 0x%x set to 0x%x\n",
sbf_port, v);