Re: page size change on MIPS

[David Daney <ddaney@caviumnetworks.com>]

On 01/24/2011 07:02 AM, naveen yadav wrote:
> Hi All,
>
>
> we are using mips32r2  so I want to know which all pages size it can support?
> When I modify arch/mips/Kconfig.  it boot sucessfully on 16KB page
> size. but hang/not boot crash when change page size to 8KB,32KB and 64
> KB.

I don't think 8KB and 32KB work on most mips32r2 processors.  You would 
have to check the processor manual to be sure.


>
> We are using 2.6.30 kernel.
>
> At Page Size 8KB and 32KB  it hang in unpack_to_rootfs() function of
> init/initramfs.c
>
> 64KB it hangs when execute init  Kernel panic - not syncing: Attempted
> to kill init!

I regularly run 4K, 16K, and 64K page sizes with a Debian rootfs.  If 
you run with a broken uClibc toolchain that doesn't support larger 
pages, it will of course fail.  In this case the problem is with your 
toolchain, not the kernel.

David Daney


>
> config PAGE_SIZE_4KB
>          bool "4kB"
>          help
>           This option select the standard 4kB Linux page size.  On some
>           R3000-family processors this is the only available page size.  Using
>           4kB page size will minimize memory consumption and is therefore
>           recommended for low memory systems.
>
> config PAGE_SIZE_8KB
>          bool "8kB"
>         depends on (EXPERIMENTAL&&  CPU_R8000) || CPU_CAVIUM_OCTEON
>          help
>            Using 8kB page size will result in higher performance kernel at
>            the price of higher memory consumption.  This option is available
>            only on R8000 and cnMIPS processors.  Note that you will need a
>            suitable Linux distribution to support this.
>
> config PAGE_SIZE_16KB
>          bool "16kB"
>         depends on !CPU_R3000&&  !CPU_TX39XX
>          help
>            Using 16kB page size will result in higher performance kernel at
>            the price of higher memory consumption.  This option is available on
>            all non-R3000 family processors.  Note that you will need a suitable
>            Linux distribution to support this.
>
> config PAGE_SIZE_32KB
>          bool "32kB"
>          help
>            Using 32kB page size will result in higher performance kernel at
>            the price of higher memory consumption.  This option is available
>            only on cnMIPS cores.  Note that you will need a suitable Linux
>            distribution to support this.
>
> config PAGE_SIZE_64KB
>          bool "64kB"
>         depends on EXPERIMENTAL&&  !CPU_R3000&&  !CPU_TX39XX
>          help
>            Using 64kB page size will result in higher performance kernel at
>            the price of higher memory consumption.  This option is available on
>            all non-R3000 family processor.  Not that at the time of this
>            writing this option is still high experimental.
>
>