linux-kernel - Re: linux-next: parsing mem=700M broken

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Message-Id: <200812252210.36367.rusty@rustcorp.com.au>
Date:	Thu, 25 Dec 2008 22:10:35 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Hugh Dickins <hugh@...itas.com>,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: linux-next: parsing mem=700M broken

On Wednesday 24 December 2008 18:39:04 Yinghai Lu wrote:
> for cpu caps on boot cpu setup still need

OK, how about these?  I cleaned up description a little, and put
it in own function.

Subject: [PATCH] x86: clean up setup_clear/force_cpu_cap handling
From: Yinghai Lu <yinghai.lu@...nel.org>

Impact: fix and cleanup

setup_force_cpu_cap() only has one user (xen) but it should not reuse
cleared_cpu_cpus.  It will have problems for smp.

Need to have cpu_cpus_set array too, and need to combine it before
we AND into boot_cpu_data.x86_capability.

Signed-off-by: Yinghai Lu <yinghai.lu@...nel.org>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
 arch/x86/include/asm/cpufeature.h |    4 ++--
 arch/x86/include/asm/processor.h  |    3 ++-
 arch/x86/kernel/cpu/common.c      |   17 ++++++++++++-----
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -188,11 +188,11 @@ extern const char * const x86_power_flag
 #define clear_cpu_cap(c, bit)	clear_bit(bit, (unsigned long *)((c)->x86_capability))
 #define setup_clear_cpu_cap(bit) do { \
 	clear_cpu_cap(&boot_cpu_data, bit);	\
-	set_bit(bit, (unsigned long *)cleared_cpu_caps); \
+	set_bit(bit, (unsigned long *)cpu_caps_cleared); \
 } while (0)
 #define setup_force_cpu_cap(bit) do { \
 	set_cpu_cap(&boot_cpu_data, bit);	\
-	clear_bit(bit, (unsigned long *)cleared_cpu_caps);	\
+	set_bit(bit, (unsigned long *)cpu_caps_set);	\
 } while (0)
 
 #define cpu_has_fpu		boot_cpu_has(X86_FEATURE_FPU)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -130,7 +130,8 @@ extern struct cpuinfo_x86	new_cpu_data;
 extern struct cpuinfo_x86	new_cpu_data;
 
 extern struct tss_struct	doublefault_tss;
-extern __u32			cleared_cpu_caps[NCAPINTS];
+extern __u32			cpu_caps_cleared[NCAPINTS];
+extern __u32			cpu_caps_set[NCAPINTS];
 
 #ifdef CONFIG_SMP
 DECLARE_PER_CPU(struct cpuinfo_x86, cpu_info);
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -219,7 +219,8 @@ static char __cpuinit *table_lookup_mode
 	return NULL;		/* Not found */
 }
 
-__u32 cleared_cpu_caps[NCAPINTS] __cpuinitdata;
+__u32 cpu_caps_cleared[NCAPINTS] __cpuinitdata;
+__u32 cpu_caps_set[NCAPINTS] __cpuinitdata;
 
 /* Current gdt points %fs at the "master" per-cpu area: after this,
  * it's on the real one. */
@@ -512,6 +513,16 @@ static void __cpuinit identify_cpu_witho
 #endif
 }
 
+static void __cpuinit override_capabilities(u32 x86_capability[])
+{
+	unsigned int i;
+
+	for (i = 0; i < NCAPINTS; i++) {
+		x86_capability[i] &= ~cpu_caps_cleared[i];
+		x86_capability[i] |= cpu_caps_set[i];
+	}
+}
+
 /*
  * Do minimum CPU detection early.
  * Fields really needed: vendor, cpuid_level, family, model, mask,
@@ -703,6 +714,9 @@ static void __cpuinit identify_cpu(struc
 	detect_ht(c);
 #endif
 
+	/* Command-line override before we AND into smp all cpus cap. */
+	override_capabilities(c->x86_capability);
+
 	/*
 	 * On SMP, boot_cpu_data holds the common feature set between
 	 * all CPUs; so make sure that we indicate which features are
@@ -714,10 +728,6 @@ static void __cpuinit identify_cpu(struc
 		for (i = 0; i < NCAPINTS; i++)
 			boot_cpu_data.x86_capability[i] &= c->x86_capability[i];
 	}
-
-	/* Clear all flags overriden by options */
-	for (i = 0; i < NCAPINTS; i++)
-		c->x86_capability[i] &= ~cleared_cpu_caps[i];
 
 #ifdef CONFIG_X86_MCE
 	/* Init Machine Check Exception if available. */


Subject: x86: override_capabilities in early_identify_cpu
From: Rusty Russell <rusty@...tcorp.com.au>

Impact: future-proof

This does nothing at the moment, but once early_param() are parsed before
setup_arch, it will ensure we respect commandline overrides on the boot
cpu's capabilities.

Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Cc: Yinghai Lu <yinghai.lu@...nel.org>

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -559,6 +559,8 @@ static void __init early_identify_cpu(st
 
 	if (this_cpu->c_early_init)
 		this_cpu->c_early_init(c);
+
+	override_capabilities(c->x86_capability);
 
 	validate_pat_support(c);
 
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