From: Dave Hansen <dave.hansen@linux.intel.com>
To: linux-kernel@vger.kernel.org
Cc: Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Juergen Gross <jgross@suse.com>,
virtualization@lists.linux.dev,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: [PATCH 7/8] x86/msr: Remove old crusty comment
Date: Fri, 20 Mar 2026 12:03:40 -0700 [thread overview]
Message-ID: <20260320190340.0C7B7CA5@davehans-spike.ostc.intel.com> (raw)
In-Reply-To: <20260320190330.A97C443B@davehans-spike.ostc.intel.com>
From: Dave Hansen <dave.hansen@linux.intel.com>
I'm not sure any of this makes sense any more. The kernel only
runs on "586 and better". The comment about gcc optimization is
hopefully decades out of date too.
Really, the only reason to keep the wonky semantics where the
parameters get modified is to avoid all the churn to make them sane.
Not gcc. gcc was probably a bad reason, even back in the day because
MSRs are mostly very slow and have always been very slow. A few
extra bytes of register shuffling was probably never measurable.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
---
b/arch/x86/include/asm/msr.h | 6 ------
1 file changed, 6 deletions(-)
diff -puN arch/x86/include/asm/msr.h~rdmsr-dups-10 arch/x86/include/asm/msr.h
--- a/arch/x86/include/asm/msr.h~rdmsr-dups-10 2026-03-20 11:24:21.571905418 -0700
+++ b/arch/x86/include/asm/msr.h 2026-03-20 11:24:21.574905551 -0700
@@ -187,12 +187,6 @@ static inline u64 native_read_pmc(int co
#define raw_write_msr_safe native_write_msr_safe
#define raw_read_pmc native_read_pmc
-/*
- * Access to machine-specific registers (available on 586 and better only)
- * Note: the rd* operations modify the parameters directly (without using
- * pointer indirection), this allows gcc to optimize better
- */
-
#endif /* !CONFIG_PARAVIRT_XXL */
/*
_
next prev parent reply other threads:[~2026-03-20 19:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-20 19:03 [PATCH 0/8] x86/msr: Consolidate native/paravirt MSR functions Dave Hansen
2026-03-20 19:03 ` [PATCH 1/8] x86/msr: Use "raw_" names for calls to native_* functions Dave Hansen
2026-03-20 19:03 ` [PATCH 2/8] x86/msr: Consolidate rdmsr() definitions Dave Hansen
2026-03-20 19:03 ` [PATCH 3/8] x86/msr: Consolidate rdmsr_safe() implementations Dave Hansen
2026-03-20 19:03 ` [PATCH 4/8] x86/msr: Consolidate rdmsrq() implementations Dave Hansen
2026-03-20 19:03 ` [PATCH 5/8] x86/msr: Consolidate {rd,wr}msr[q]_safe() implementations Dave Hansen
2026-03-20 19:03 ` [PATCH 6/8] x86/msr: Consolidate rdpmc() implementations Dave Hansen
2026-03-20 19:03 ` Dave Hansen [this message]
2026-03-20 19:03 ` [PATCH 8/8] x86/msr: Remove duplicate #include Dave Hansen
2026-03-20 23:33 ` [PATCH 0/8] x86/msr: Consolidate native/paravirt MSR functions Borislav Petkov
2026-03-20 23:39 ` Dave Hansen
2026-03-21 6:23 ` Jürgen Groß
2026-03-23 15:22 ` Juergen Gross
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