From: Matthew Whitehead <tedheadster@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@kernel.org, tglx@linutronix.de, peterz@infradead.org,
luto@amacapital.net, bp@alien8.de, hpa@zytor.com,
Matthew Whitehead <tedheadster@gmail.com>
Subject: [PATCH v2 1/2] x86/cpu: Use correct macros for Cyrix calls
Date: Fri, 21 Sep 2018 17:20:40 -0400 [thread overview]
Message-ID: <20180921212041.13096-2-tedheadster@gmail.com> (raw)
In-Reply-To: <20180921212041.13096-1-tedheadster@gmail.com>
There are comments in processor-cyrix.h advising you to _not_ make calls
using the deprecated macros in this style:
setCx86_old(CX86_CCR4, getCx86_old(CX86_CCR4) | 0x80);
This is because it expands the macro into a non-functioning calling
sequence. The calling order must be:
outb(CX86_CCR2, 0x22);
inb(0x23);
From the comments:
* When using the old macros a line like
* setCx86(CX86_CCR2, getCx86(CX86_CCR2) | 0x88);
* gets expanded to:
* do {
* outb((CX86_CCR2), 0x22);
* outb((({
* outb((CX86_CCR2), 0x22);
* inb(0x23);
* }) | 0x88), 0x23);
* } while (0);
The new macros fix this problem, so we use them instead.
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Matthew Whitehead <tedheadster@gmail.com>
---
arch/x86/kernel/cpu/cyrix.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/cyrix.c b/arch/x86/kernel/cpu/cyrix.c
index 8949b7ae6d92..d12226f60168 100644
--- a/arch/x86/kernel/cpu/cyrix.c
+++ b/arch/x86/kernel/cpu/cyrix.c
@@ -437,7 +437,7 @@ static void cyrix_identify(struct cpuinfo_x86 *c)
/* enable MAPEN */
setCx86(CX86_CCR3, (ccr3 & 0x0f) | 0x10);
/* enable cpuid */
- setCx86_old(CX86_CCR4, getCx86_old(CX86_CCR4) | 0x80);
+ setCx86(CX86_CCR4, getCx86(CX86_CCR4) | 0x80);
/* disable MAPEN */
setCx86(CX86_CCR3, ccr3);
local_irq_restore(flags);
--
2.16.4
next prev parent reply other threads:[~2018-09-21 21:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-21 21:20 [PATCH v2 0/2] x86/cpu: Enable cpuid on Cyrix 6x86/6x86L processors Matthew Whitehead
2018-09-21 21:20 ` Matthew Whitehead [this message]
2018-09-22 9:57 ` [tip:x86/cpu] x86/CPU: Use correct macros for Cyrix calls tip-bot for Matthew Whitehead
2018-09-21 21:20 ` [PATCH v2 2/2] x86/cpu: Change query logic so cpuid is enabled before testing Matthew Whitehead
2018-09-21 21:54 ` Andy Lutomirski
2018-09-22 9:58 ` [tip:x86/cpu] x86/CPU: Change query logic so CPUID " tip-bot for Matthew Whitehead
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