Some questions about high memory
hi all: I am trying to write a driver for my block device which dma support high memory copying. I have register my device as "blk_bounce_any". But my driver cannot see block layer pass high memory to me so far. Is there any user/kernel test program which will purposely send high memory for driver to use? or is there any flag when opening a file in user mode that will use high memory? -- Thanks for your help in advance,
Hi... On Fri, Apr 6, 2012 at 09:19, loody <miloody@gmail.com> wrote:
hi all: I am trying to write a driver for my block device which dma support high memory copying. I have register my device as "blk_bounce_any". But my driver cannot see block layer pass high memory to me so far.
perhaps because you need to kmap them first? BTW, is it 32 bit or 64 bit Linux kernel?
Is there any user/kernel test program which will purposely send high memory for driver to use? or is there any flag when opening a file in user mode that will use high memory?
I recheck mmap and mmap manual page and I found none of such flag -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
hi mulyadi 2012/4/6 Mulyadi Santosa <mulyadi.santosa@gmail.com>:
Hi...
On Fri, Apr 6, 2012 at 09:19, loody <miloody@gmail.com> wrote:
hi all: I am trying to write a driver for my block device which dma support high memory copying. I have register my device as "blk_bounce_any". But my driver cannot see block layer pass high memory to me so far.
perhaps because you need to kmap them first? If I remember correctly, Kmap is used for mapping high memory into kernel virtual memory. Isn't that the job for block layer?
I thought once I declare my block device as "blk_bounce_any", the block layer will pass the physical address of high memory to device.
BTW, is it 32 bit or 64 bit Linux kernel?
32-bits linux kernel.
Is there any user/kernel test program which will purposely send high memory for driver to use? or is there any flag when opening a file in user mode that will use high memory?
I recheck mmap and mmap manual page and I found none of such flag
does that mean mmap can specify which memory to map? if that is true, which range I should use?
-- regards,
Mulyadi Santosa Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
Appreciate your help
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