Re: how to allocate 9MB of memory in kernel ?

[Misbah khan <misbah_khan@engineer.com>]

If you SDRAM is you main memory, you need vmalloc and remap_vmalloc_range.
If the SDRAM is not your main memory but some I/O attached buffer, you need
ioremap/of_iomap and remap_pfn_range.

My SDRAM is the main memory of which 9MB i have to allocate in the driver. 

If i allocate 9BM using vmalloc and remap to user space how should it
address to the 9MB 
SDRAM contigues address which i need to map for user access ? 


Arnd Bergmann wrote:
> 
> On Tuesday 22 July 2008, Misbah khan wrote:
>> First of all let me thank you for your valuable suggessions ...
>> 
>> 1. I wanted to allocate 9MB in kernel and wanted that memory to be mapped
>> to
>> the physically continews SDRAM memory. but till now i could not found a
>> way
>> to do so ???
>> 
>> 2. So i thought to use ioremap to map SDRAM and make it accessible to
>> user
>> using mmap technique but there is only one doubt and that is will it be
>> secure and stable and whether it is a right way of doing ???
> 
> As I have told you a few times now, you *either* allocate the memory *or*
> ioremap it, NOT BOTH!!!
> 
> If you SDRAM is you main memory, you need vmalloc and remap_vmalloc_range.
> If the SDRAM is not your main memory but some I/O attached buffer, you
> need
> ioremap/of_iomap and remap_pfn_range.
> 
> 	Arnd <><
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> 
> 

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