Re: [PATCH] cheat for support of more than 256MB memory

[Tian <tiansm@lemote.com>]

Tian wrote:
> Tian wrote:
>> Ralf Baechle wrote:
>>> On Wed, Jun 06, 2007 at 08:38:18AM +0200, Franck Bui-Huu wrote:
>>>
>>>  
>>>>> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
>>>>> index 4975da0..62ef100 100644
>>>>> --- a/arch/mips/kernel/setup.c
>>>>> +++ b/arch/mips/kernel/setup.c
>>>>> @@ -509,6 +509,14 @@ static void __init resource_init(void)
>>>>>                res->end = end;
>>>>>
>>>>>                res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
>>>>> +#if defined(CONFIG_LEMOTE_FULONG) && defined(CONFIG_64BIT)
>>>>> +               /* to keep memory continous, we tell system 
>>>>> 0x10000000 - 0x20000000 is reserved
>>>>> +                * for memory, in fact it is io region, don't 
>>>>> occupy it
>>>>> +                *
>>>>> +                * SPARSEMEM?
>>>>>       
>>>> Definetly yes ! It has been designed for such issue and it should save
>>>> you some memory.
>>>>     
>>>
>>> A hole of 256MB size in the memory address map will cost 3.5MB with 
>>> a 64-bit
>>> kernel.  The other reason why I don't like this patch is that it drags
>>> platform specific code into the generic MIPS code.
>>>
>>>   Ralf
>>>
>>>
>>>   
>> we use 16k page，so it's cheaper than that:)
>>
>> Before I work out sparse memory solution, I think I can drop this 
>> patch and make some trivial fix of the first patch.
>>
>> Subject: [PATCH] simply ignore the memory hole
>>
>> Signed-off-by: Songmao Tian <tiansm@lemote.com>
>> ---
>> arch/mips/lemote/lm2e/setup.c |    1 -
>> 1 files changed, 0 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/mips/lemote/lm2e/setup.c 
>> b/arch/mips/lemote/lm2e/setup.c
>> index 3030518..2498bbf 100644
>> --- a/arch/mips/lemote/lm2e/setup.c
>> +++ b/arch/mips/lemote/lm2e/setup.c
>> @@ -112,7 +112,6 @@ void __init plat_mem_setup(void)
>>     add_memory_region(0x0, (memsize << 20), BOOT_MEM_RAM);
>> #ifdef CONFIG_64BIT
>>     if (highmemsize > 0) {
>> -        add_memory_region(0x10000000, 0x10000000, BOOT_MEM_RESERVED);
>>         add_memory_region(0x20000000, highmemsize << 20, BOOT_MEM_RAM);
>>     }
>> #endif
>>
>>
>>
> It seems it's no need to modify code, just config to use
> sparse memory will be ok, paging_init can handle the
> non-flat-memory situatioins, and i notify the pages drop down as 
> expected.
Well, I mean notice...forgive me, I don't speak english often:)
>
>
> Subject: [PATCH] use SPARSEMEM to deal with the memory hole of 
> peripheral IO
>
> Signed-off-by: Songmao Tian <tiansm@lemote.com>
> ---
> arch/mips/Kconfig                  |    1 +
> arch/mips/configs/fulong_defconfig |   13 +++++++------
> 2 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 16f1861..376cbd6 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -957,6 +957,7 @@ config CPU_LOONGSON2
>     depends on SYS_HAS_CPU_LOONGSON2
>     select CPU_SUPPORTS_32BIT_KERNEL
>     select CPU_SUPPORTS_64BIT_KERNEL
> +    select ARCH_SPARSEMEM_ENABLE
>     select CPU_SUPPORTS_HIGHMEM
>
> config CPU_MIPS32_R1
> diff --git a/arch/mips/configs/fulong_defconfig 
> b/arch/mips/configs/fulong_defconfig
> index cd6563a..92d9772 100644
> --- a/arch/mips/configs/fulong_defconfig
> +++ b/arch/mips/configs/fulong_defconfig
> @@ -1,7 +1,7 @@
> #
> # Automatically generated make config: don't edit
> # Linux kernel version: 2.6.22-rc3
> -# Wed Jun  6 11:42:13 2007
> +# Fri Jun  8 15:09:24 2007
> #
> CONFIG_MIPS=y
>
> @@ -118,13 +118,14 @@ CONFIG_GENERIC_IRQ_PROBE=y
> CONFIG_CPU_SUPPORTS_HIGHMEM=y
> CONFIG_SYS_SUPPORTS_HIGHMEM=y
> CONFIG_ARCH_FLATMEM_ENABLE=y
> +CONFIG_ARCH_SPARSEMEM_ENABLE=y
> CONFIG_SELECT_MEMORY_MODEL=y
> -CONFIG_FLATMEM_MANUAL=y
> +# CONFIG_FLATMEM_MANUAL is not set
> # CONFIG_DISCONTIGMEM_MANUAL is not set
> -# CONFIG_SPARSEMEM_MANUAL is not set
> -CONFIG_FLATMEM=y
> -CONFIG_FLAT_NODE_MEM_MAP=y
> -# CONFIG_SPARSEMEM_STATIC is not set
> +CONFIG_SPARSEMEM_MANUAL=y
> +CONFIG_SPARSEMEM=y
> +CONFIG_HAVE_MEMORY_PRESENT=y
> +CONFIG_SPARSEMEM_STATIC=y
> CONFIG_SPLIT_PTLOCK_CPUS=4
> CONFIG_RESOURCES_64BIT=y
> CONFIG_ZONE_DMA_FLAG=0
>
>