{PATCH] x86: print out initial max_pfn_mapped

{PATCH] x86: print out initial max_pfn_mapped

[Yinghai Lu]

Impact: more debug info

check range that is mapped before init_memory_mapping().
also make 64bit have max_pfn_mapped assigned before that calling

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 arch/x86/kernel/setup.c |    3 +++
 arch/x86/mm/init.c      |    7 +++----
 2 files changed, 6 insertions(+), 4 deletions(-)

Index: linux-2.6/arch/x86/kernel/setup.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/setup.c
+++ linux-2.6/arch/x86/kernel/setup.c
@@ -836,12 +836,15 @@ void __init setup_arch(char **cmdline_p)
 		max_low_pfn = max_pfn;
 
 	high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
+	max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;
 #endif
 
 #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
 	setup_bios_corruption_check();
 #endif
 
+	printk(KERN_DEBUG "initial memory mapped %lx\n", max_pfn_mapped<<PAGE_SHIFT);
+
 	/* max_pfn_mapped is updated here */
 	max_low_pfn_mapped = init_memory_mapping(0, max_low_pfn<<PAGE_SHIFT);
 	max_pfn_mapped = max_low_pfn_mapped;
Index: linux-2.6/arch/x86/mm/init.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init.c
+++ linux-2.6/arch/x86/mm/init.c
@@ -65,12 +65,11 @@ static void __init find_early_table_spac
 	 */
 #ifdef CONFIG_X86_32
 	start = 0x7000;
-	e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
-					tables, PAGE_SIZE);
-#else /* CONFIG_X86_64 */
+#else
 	start = 0x8000;
-	e820_table_start = find_e820_area(start, end, tables, PAGE_SIZE);
 #endif
+	e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
+					tables, PAGE_SIZE);
 	if (e820_table_start == -1UL)
 		panic("Cannot find space for the kernel page tables");
 

Re: {PATCH] x86: print out initial max_pfn_mapped

[H. Peter Anvin]

Yinghai Lu wrote:
> Impact: more debug info
> 
> check range that is mapped before init_memory_mapping().
> also make 64bit have max_pfn_mapped assigned before that calling
> 
> Index: linux-2.6/arch/x86/mm/init.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/mm/init.c
> +++ linux-2.6/arch/x86/mm/init.c
> @@ -65,12 +65,11 @@ static void __init find_early_table_spac
>  	 */
>  #ifdef CONFIG_X86_32
>  	start = 0x7000;
> -	e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
> -					tables, PAGE_SIZE);
> -#else /* CONFIG_X86_64 */
> +#else
>  	start = 0x8000;
> -	e820_table_start = find_e820_area(start, end, tables, PAGE_SIZE);
>  #endif
> +	e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
> +					tables, PAGE_SIZE);
>  	if (e820_table_start == -1UL)
>  		panic("Cannot find space for the kernel page tables");
>  

This doesn't seem to match anything anywhere in the description.
Furthermore, why do we even have a different starting address for
different architectures?  If anything, this starting address is way too
low (hogging ZONE_DMA and all that...)

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

Re: {PATCH] x86: print out initial max_pfn_mapped

[Yinghai Lu]

H. Peter Anvin wrote:
> Yinghai Lu wrote:
>> Impact: more debug info
>>
>> check range that is mapped before init_memory_mapping().
>> also make 64bit have max_pfn_mapped assigned before that calling
>>
>> Index: linux-2.6/arch/x86/mm/init.c
>> ===================================================================
>> --- linux-2.6.orig/arch/x86/mm/init.c
>> +++ linux-2.6/arch/x86/mm/init.c
>> @@ -65,12 +65,11 @@ static void __init find_early_table_spac
>>  	 */
>>  #ifdef CONFIG_X86_32
>>  	start = 0x7000;
>> -	e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
>> -					tables, PAGE_SIZE);
>> -#else /* CONFIG_X86_64 */
>> +#else
>>  	start = 0x8000;
>> -	e820_table_start = find_e820_area(start, end, tables, PAGE_SIZE);
>>  #endif
>> +	e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
>> +					tables, PAGE_SIZE);
>>  	if (e820_table_start == -1UL)
>>  		panic("Cannot find space for the kernel page tables");
>>  
> 
> This doesn't seem to match anything anywhere in the description.
> Furthermore, why do we even have a different starting address for
> different architectures?  If anything, this starting address is way too
> low (hogging ZONE_DMA and all that...)
> 


>> also make 64bit have max_pfn_mapped assigned before that calling

so find_e820_area() could use max_pfn_mapped for 64 bit too.

for 64bit, you could use start from 16M for searching free range for left page table. right now
for 32bit, you may need to increase initial max_pfn_mapped to 32M (?) so could start searching from 16M.
need some code for head_32.S
anyway that will be another patch.

YH

[tip:x86/mm] x86: clean up and and print out initial max_pfn_mapped

[tip-bot for Yinghai Lu]

Commit-ID:  80989ce0643c1034822f3e339ed8d790b649abe1
Gitweb:     http://git.kernel.org/tip/80989ce0643c1034822f3e339ed8d790b649abe1
Author:     Yinghai Lu <yinghai@kernel.org>
AuthorDate: Sat, 9 May 2009 23:47:42 -0700
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 11 May 2009 11:11:12 +0200

x86: clean up and and print out initial max_pfn_mapped

Do this so we can check the range that is mapped before
init_memory_mapping().

To be able to print out meaningful info, we first have to fix
64-bit to have max_pfn_mapped assigned before that call. This
also unifies the code-path a bit.

[ Impact: print more debug info, cleanup ]

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <49BF0978.40605@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 arch/x86/kernel/setup.c |    4 ++++
 arch/x86/mm/init.c      |    7 +++----
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 0d77e56..4031d6c 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -862,12 +862,16 @@ void __init setup_arch(char **cmdline_p)
 		max_low_pfn = max_pfn;
 
 	high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
+	max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;
 #endif
 
 #ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
 	setup_bios_corruption_check();
 #endif
 
+	printk(KERN_DEBUG "initial memory mapped : 0 - %08lx\n",
+			max_pfn_mapped<<PAGE_SHIFT);
+
 	reserve_brk();
 
 	/* max_pfn_mapped is updated here */
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 95f5ecf..92d2108 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -132,12 +132,11 @@ static void __init find_early_table_space(unsigned long end, int use_pse,
 	 */
 #ifdef CONFIG_X86_32
 	start = 0x7000;
-	e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
-					tables, PAGE_SIZE);
-#else /* CONFIG_X86_64 */
+#else
 	start = 0x8000;
-	e820_table_start = find_e820_area(start, end, tables, PAGE_SIZE);
 #endif
+	e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
+					tables, PAGE_SIZE);
 	if (e820_table_start == -1UL)
 		panic("Cannot find space for the kernel page tables");