[v3,7/8] book3e/kexec/kdump: redefine VIRT_PHYS_OFFSET

Book3e is always aligned 1GB to create TLB so we should
use (KERNELBASE - MEMORY_START) as VIRT_PHYS_OFFSET to
get __pa/__va properly while boot kdump.

Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
---
 arch/powerpc/include/asm/page.h |    2 ++
 1 file changed, 2 insertions(+)

> -----Original Message-----
> From: Linuxppc-dev [mailto:linuxppc-dev-
> bounces+bharat.bhushan=freescale.com@lists.ozlabs.org] On Behalf Of Tiejun Chen
> Sent: Tuesday, July 09, 2013 1:33 PM
> To: benh@kernel.crashing.org
> Cc: linuxppc-dev@lists.ozlabs.org; linux-kernel@vger.kernel.org
> Subject: [v3][PATCH 7/8] book3e/kexec/kdump: redefine VIRT_PHYS_OFFSET
> 
> Book3e is always aligned 1GB to create TLB so we should
> use (KERNELBASE - MEMORY_START) as VIRT_PHYS_OFFSET to
> get __pa/__va properly while boot kdump.
> 
> Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
> ---
>  arch/powerpc/include/asm/page.h |    2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
> index 988c812..5b00081 100644
> --- a/arch/powerpc/include/asm/page.h
> +++ b/arch/powerpc/include/asm/page.h
> @@ -112,6 +112,8 @@ extern long long virt_phys_offset;
>  /* See Description below for VIRT_PHYS_OFFSET */
>  #ifdef CONFIG_RELOCATABLE_PPC32
>  #define VIRT_PHYS_OFFSET virt_phys_offset
> +#elif defined(CONFIG_PPC_BOOK3E_64)
> +#define VIRT_PHYS_OFFSET (KERNELBASE - MEMORY_START)

Can you please explain this code a bit more. I am not understanding this part:)

-Bharat

>  #else
>  #define VIRT_PHYS_OFFSET (KERNELBASE - PHYSICAL_START)
>  #endif
> --
> 1.7.9.5
> 
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

On 07/10/2013 01:20 PM, Bhushan Bharat-R65777 wrote:
>
>
>> -----Original Message-----
>> From: Linuxppc-dev [mailto:linuxppc-dev-
>> bounces+bharat.bhushan=freescale.com@lists.ozlabs.org] On Behalf Of Tiejun Chen
>> Sent: Tuesday, July 09, 2013 1:33 PM
>> To: benh@kernel.crashing.org
>> Cc: linuxppc-dev@lists.ozlabs.org; linux-kernel@vger.kernel.org
>> Subject: [v3][PATCH 7/8] book3e/kexec/kdump: redefine VIRT_PHYS_OFFSET
>>
>> Book3e is always aligned 1GB to create TLB so we should
>> use (KERNELBASE - MEMORY_START) as VIRT_PHYS_OFFSET to
>> get __pa/__va properly while boot kdump.
>>
>> Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com>
>> ---
>>   arch/powerpc/include/asm/page.h |    2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
>> index 988c812..5b00081 100644
>> --- a/arch/powerpc/include/asm/page.h
>> +++ b/arch/powerpc/include/asm/page.h
>> @@ -112,6 +112,8 @@ extern long long virt_phys_offset;
>>   /* See Description below for VIRT_PHYS_OFFSET */
>>   #ifdef CONFIG_RELOCATABLE_PPC32
>>   #define VIRT_PHYS_OFFSET virt_phys_offset
>> +#elif defined(CONFIG_PPC_BOOK3E_64)
>> +#define VIRT_PHYS_OFFSET (KERNELBASE - MEMORY_START)
>
> Can you please explain this code a bit more. I am not understanding this part:)

Nothing is special, we only need to redefine this to make sure __va()/__pa() can 
work well for BOOk3E-64 in BOOKE case:

#ifdef CONFIG_BOOKE
#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) + VIRT_PHYS_OFFSET))
#define __pa(x) ((unsigned long)(x) - VIRT_PHYS_OFFSET)

And the arch/powerpc/include/asm/page.h file has more descriptions inline :)

Tiejun

On Tue, 2013-07-09 at 16:03 +0800, Tiejun Chen wrote:
> Book3e is always aligned 1GB to create TLB so we should
> use (KERNELBASE - MEMORY_START) as VIRT_PHYS_OFFSET to
> get __pa/__va properly while boot kdump.

What if MEMORY_START - PHYSICAL_START >= 1 GiB?

What about the comment that says we can't use MEMORY_START before
parsing the device tree?

-Scott