[patch 1/2] x86: head_64.S cleanup - use straight move to CR4 register

[patch 1/2] x86: head_64.S cleanup - use straight move to CR4 register

[Cyrill Gorcunov]

[-- Attachment #1: x86-head-64-S-flags --]
[-- Type: text/plain, Size: 710 bytes --]

There is no need for testing the values because we already know
what they should be. Just set them in straight way.

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---

Index: linux-2.6.git/arch/x86/kernel/head_64.S
===================================================================
--- linux-2.6.git.orig/arch/x86/kernel/head_64.S	2008-05-13 19:17:31.000000000 +0400
+++ linux-2.6.git/arch/x86/kernel/head_64.S	2008-05-13 19:35:11.000000000 +0400
@@ -155,9 +155,7 @@ ENTRY(secondary_startup_64)
 	 */
 
 	/* Enable PAE mode and PGE */
-	xorq	%rax, %rax
-	btsq	$5, %rax
-	btsq	$7, %rax
+	movq	$(X86_CR4_PAE | X86_CR4_PGE), %rax
 	movq	%rax, %cr4
 
 	/* Setup early boot stage 4 level pagetables. */

-- 

[patch 2/2] x86: head_64.S cleanup - use PMD_SHIFT instead of numeric constant

[Cyrill Gorcunov]

[-- Attachment #1: x86-head-64-pmd --]
[-- Type: text/plain, Size: 754 bytes --]

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---

Index: linux-2.6.git/arch/x86/kernel/head_64.S
===================================================================
--- linux-2.6.git.orig/arch/x86/kernel/head_64.S	2008-05-13 20:05:04.000000000 +0400
+++ linux-2.6.git/arch/x86/kernel/head_64.S	2008-05-13 20:22:27.000000000 +0400
@@ -322,11 +322,11 @@ early_idt_ripmsg:
 ENTRY(name)
 
 /* Automate the creation of 1 to 1 mapping pmd entries */
-#define PMDS(START, PERM, COUNT)		\
-	i = 0 ;					\
-	.rept (COUNT) ;				\
-	.quad	(START) + (i << 21) + (PERM) ;	\
-	i = i + 1 ;				\
+#define PMDS(START, PERM, COUNT)			\
+	i = 0 ;						\
+	.rept (COUNT) ;					\
+	.quad	(START) + (i << PMD_SHIFT) + (PERM) ;	\
+	i = i + 1 ;					\
 	.endr
 
 	/*

-- 

Re: [patch 1/2] x86: head_64.S cleanup - use straight move to CR4 register

[H. Peter Anvin]

Cyrill Gorcunov wrote:
> There is no need for testing the values because we already know
> what they should be. Just set them in straight way.

He isn't testing them, he's setting individual bits.

Either of these is pretty silly; the right way to do this is:

	movl	$(X86_CR4_PAE|X86_CR4_PGE), %eax
	movq	%rax, %cr4

A movl in 64-bit mode zero extends.

	-hpa

Re: [patch 1/2] x86: head_64.S cleanup - use straight move to CR4 register

[Cyrill Gorcunov]

[H. Peter Anvin - Tue, May 13, 2008 at 10:03:42AM -0700]
> Cyrill Gorcunov wrote:
>> There is no need for testing the values because we already know
>> what they should be. Just set them in straight way.
>
> He isn't testing them, he's setting individual bits.

not exactly - bts: bit test and set

>
> Either of these is pretty silly; the right way to do this is:
>
> 	movl	$(X86_CR4_PAE|X86_CR4_PGE), %eax
> 	movq	%rax, %cr4
>
> A movl in 64-bit mode zero extends.
>
> 	-hpa
>
ok, thanks Peter, i'll update in minute ;)

		- Cyrill -

Re: [patch 1/2] x86: head_64.S cleanup - use straight move to CR4 register

[Cyrill Gorcunov]

[H. Peter Anvin - Tue, May 13, 2008 at 10:03:42AM -0700]
> Cyrill Gorcunov wrote:
>> There is no need for testing the values because we already know
>> what they should be. Just set them in straight way.
>
> He isn't testing them, he's setting individual bits.
>
> Either of these is pretty silly; the right way to do this is:
>
> 	movl	$(X86_CR4_PAE|X86_CR4_PGE), %eax
> 	movq	%rax, %cr4
>
> A movl in 64-bit mode zero extends.
>
> 	-hpa
>

Here is updated version
---
[PATCH] x86: head_64.S cleanup - use straight move to CR4 register

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---

Index: linux-2.6.git/arch/x86/kernel/head_64.S
===================================================================
--- linux-2.6.git.orig/arch/x86/kernel/head_64.S	2008-05-13 20:04:23.000000000 +0400
+++ linux-2.6.git/arch/x86/kernel/head_64.S	2008-05-13 21:08:20.000000000 +0400
@@ -155,9 +155,7 @@ ENTRY(secondary_startup_64)
 	 */
 
 	/* Enable PAE mode and PGE */
-	xorq	%rax, %rax
-	btsq	$5, %rax
-	btsq	$7, %rax
+	movl	$(X86_CR4_PAE | X86_CR4_PGE), %rax
 	movq	%rax, %cr4
 
 	/* Setup early boot stage 4 level pagetables. */

Re: [patch 1/2] x86: head_64.S cleanup - use straight move to CR4 register

[H. Peter Anvin]

Cyrill Gorcunov wrote:
> [H. Peter Anvin - Tue, May 13, 2008 at 10:03:42AM -0700]
>> Cyrill Gorcunov wrote:
>>> There is no need for testing the values because we already know
>>> what they should be. Just set them in straight way.
>> He isn't testing them, he's setting individual bits.
>>
>> Either of these is pretty silly; the right way to do this is:
>>
>> 	movl	$(X86_CR4_PAE|X86_CR4_PGE), %eax
>> 	movq	%rax, %cr4
>>
>> A movl in 64-bit mode zero extends.
>>
>> 	-hpa
>>
> 
> Here is updated version
> ---
> [PATCH] x86: head_64.S cleanup - use straight move to CR4 register
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
> ---
> 
> Index: linux-2.6.git/arch/x86/kernel/head_64.S
> ===================================================================
> --- linux-2.6.git.orig/arch/x86/kernel/head_64.S	2008-05-13 20:04:23.000000000 +0400
> +++ linux-2.6.git/arch/x86/kernel/head_64.S	2008-05-13 21:08:20.000000000 +0400
> @@ -155,9 +155,7 @@ ENTRY(secondary_startup_64)
>  	 */
>  
>  	/* Enable PAE mode and PGE */
> -	xorq	%rax, %rax
> -	btsq	$5, %rax
> -	btsq	$7, %rax
> +	movl	$(X86_CR4_PAE | X86_CR4_PGE), %rax
>  	movq	%rax, %cr4
>  

Syntax error.  %eax, not %rax.

	-hpa

Re: [patch 1/2] x86: head_64.S cleanup - use straight move to CR4 register

[Cyrill Gorcunov]

[H. Peter Anvin - Tue, May 13, 2008 at 10:11:34AM -0700]
> Cyrill Gorcunov wrote:
>> [H. Peter Anvin - Tue, May 13, 2008 at 10:03:42AM -0700]
>>> Cyrill Gorcunov wrote:
>>>> There is no need for testing the values because we already know
>>>> what they should be. Just set them in straight way.
>>> He isn't testing them, he's setting individual bits.
>>>
>>> Either of these is pretty silly; the right way to do this is:
>>>
>>> 	movl	$(X86_CR4_PAE|X86_CR4_PGE), %eax
>>> 	movq	%rax, %cr4
>>>
>>> A movl in 64-bit mode zero extends.
>>>
>>> 	-hpa
>>>
>> Here is updated version
>> ---
>> [PATCH] x86: head_64.S cleanup - use straight move to CR4 register
>> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
>> ---
>> Index: linux-2.6.git/arch/x86/kernel/head_64.S
>> ===================================================================
>> --- linux-2.6.git.orig/arch/x86/kernel/head_64.S	2008-05-13 
>> 20:04:23.000000000 +0400
>> +++ linux-2.6.git/arch/x86/kernel/head_64.S	2008-05-13 21:08:20.000000000 
>> +0400
>> @@ -155,9 +155,7 @@ ENTRY(secondary_startup_64)
>>  	 */
>>   	/* Enable PAE mode and PGE */
>> -	xorq	%rax, %rax
>> -	btsq	$5, %rax
>> -	btsq	$7, %rax
>> +	movl	$(X86_CR4_PAE | X86_CR4_PGE), %rax
>>  	movq	%rax, %cr4
>>  
>
> Syntax error.  %eax, not %rax.
>
> 	-hpa
>


Oh my, what I'm doing... sorry
Here we go

---
[PATCH] x86: head_64.S cleanup - use straight move to CR4 register

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---

Index: linux-2.6.git/arch/x86/kernel/head_64.S
===================================================================
--- linux-2.6.git.orig/arch/x86/kernel/head_64.S	2008-05-13 20:04:23.000000000 +0400
+++ linux-2.6.git/arch/x86/kernel/head_64.S	2008-05-13 21:12:39.000000000 +0400
@@ -155,9 +155,7 @@ ENTRY(secondary_startup_64)
 	 */
 
 	/* Enable PAE mode and PGE */
-	xorq	%rax, %rax
-	btsq	$5, %rax
-	btsq	$7, %rax
+	movl	$(X86_CR4_PAE | X86_CR4_PGE), %eax
 	movq	%rax, %cr4
 
 	/* Setup early boot stage 4 level pagetables. */

		- Cyrill -