>> Hi all,
>> The following link gives the memory map for the arm architecture.
>> http://www.arm.linux.org.uk/developer/memory.txt
>>
>>I have the following doubts..
>>1) Any chipset(based on arm) manufacturer(qualcom,samsung..) should follow
>>the same memory map.
>>Is it hardly constrained or can be changed?
>>Where are this constraints are implemented in the kernel source tree?
>you mean, device memory map? well AFAIK that is dictated by
>BIOS....kernel simply just follow along...
Not the device memory map..others also like vmalloc()/ioremap region, dma_alloc() (refer that link)
these regions.
i refered to qualcomm chipset memory map(based on ARM9). They just mentioned only where different devices were mapped.
They doesnt have this specifc adress space constraints for vmalloc, ioremap,dma_alloc etc.,
So i thought it is taken care by kernel.
Please tell me where these constraints will be implemented?
Another clarification, while assigning memory through vmalloc(), dma_alloc() kernel first
should check the available address space 'taking the constraints into consideration' before returning the addresses, right?
On Tue, May 31, 2011 at 12:32 PM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote:
Hi...
I am not ARM guy, but I'll see what I can share here..... hold your breath :)
you mean, device memory map? well AFAIK that is dictated by
On Tue, May 31, 2011 at 12:54, sandeep kumar <coolsandyforyou@xxxxxxxxx> wrote:
> Hi all,
> The following link gives the memory map for the arm architecture.
> http://www.arm.linux.org.uk/developer/memory.txt
>
> I have the following doubts..
> 1) Any chipset(based on arm) manufacturer(qualcom,samsung..) should follow
> the same memory map.
> Is it hardly constrained or can be changed?
> Where are this constraints are implemented in the kernel source tree?
BIOS....kernel simply just follow along...
that's true... but you need to count another limitation: addressable
>
> 2) while i was student, i read in OS concepts that, "Virtual memory gives an
> illusion to a process,
> that it has always a larger continuous address space (even more than RAM)
> available to it."
or not by the MMU or at least processor itself?
let's say you have 16 GiB of virtual memory, composed of 4 GiB of RAM
+ 12 GiB swap. Theoritically, a single process should be able to use
them all, but assuming we have no PAE enabled, an 32 bit system could
only address up to 4 GiB
Also think about fragmentation...
> So i thought i could allocate howmuch ever memory i want.
Yup.....
> But seeing the above link,i observed there is some limitation in the address
> space created by the vmalloc().
> So i m now thinking that vmalloc has some limit.
maybe my old article could shed a light further for you:
http://linuxdevcenter.com/pub/a/linux/2006/11/30/linux-out-of-memory.html
--
regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com
--
With regards,
Sandeep Kumar Anantapalli,
Senior Software Engineer,
Samsung India Software Operations,
Bangalore.
_______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
