CMEM related

Digant Desai

Hi all,

I want to reserve some fix addresses on Physical map and want to make sure kernel won't swipe it. It will be around 2 pages. I also want to access them from the drivers as we do in mmaped gpio's registers.

Can I do this using CMEM?

and what If I don't want to do CMEM is there any simplest method ?

please reply.

Thank you.

over 14 years ago

0 Digant Desai over 14 years ago

Expert 1225 points

Can I directly limit the kernel usable memory size and use the remaining space ? using "mem" bootarg?

for e.g I have 128m physical memory and I pass bootarg mem=126m then Can I use rest 2 MB for any other usage or kernel will give segmentation fault if I try to call addresses out side the range ?

0 keerti patil over 14 years ago in reply to Digant Desai

Prodigy 150 points

Hi,

Yes, you can do that. The size allocated to CMEM module depends on the total available memory. Out of the total memory, you need to reserve something for the OS

and rest you can use for CMEM.

Regards,

Kirti.

0 Digant Desai over 14 years ago in reply to keerti patil

Expert 1225 points

Thank you for the reply,

Did you mean I can do the UBOOT thing ?

0 keerti patil over 14 years ago in reply to Digant Desai

Prodigy 150 points

Hi,

Yes, you can specify "mem=" argument in your bootargs as much as required by your kernel. The rest can be used for cmem.

Regards,

kirti

0 Digant Desai over 14 years ago in reply to keerti patil

Expert 1225 points

Yes you are right , I get this point but what if I don't want to use CMEM then can I access the rest of the memory outside the boundary specified by "mem=" through Linux like mmaped registers ???

0 Digant Desai over 14 years ago in reply to Digant Desai

Expert 1225 points

Thank you for your reply,let me try this out first.

Second,

Is CMEM portable across all ARM boards ? if I want to do some experiment with my other ARM board e.g DM355 EVM kit, which don't have DSP, can I run CMEM on it just to reserve physical memory for other stuff?

If not what should I change in order to make it portable?

0 Robert Tivy over 14 years ago in reply to Digant Desai

TI__Mastermind 18260 points

Digant Desai said:

Is CMEM portable across all ARM boards ? if I want to do some experiment with my other ARM board e.g DM355 EVM kit, which don't have DSP, can I run CMEM on it just to reserve physical memory for other stuff?

Yes, CMEM is portable to all ARM boards running Linux, including the DM355. The CMEM source code contains some #ifdefs for different kernel versions, and today it supports recent 2.6.38+ kernels (in addition to older kernels, e.g., 2.6.10).

Regards,

- Rob

0 Digant Desai over 14 years ago in reply to Robert Tivy

Expert 1225 points

Even on non ti platforms??

0 Robert Tivy over 14 years ago in reply to Digant Desai

TI__Mastermind 18260 points

Digant Desai said:

Even on non ti platforms??

I would expect so, although I've never tried it. CMEM depends *only* on Linux.

Regards,

- Rob

0 Digant Desai over 14 years ago in reply to Robert Tivy

Expert 1225 points

Thank you fr quick reply.

I will try , I was concern because there is some ARM926e specific assembly level code present and what if I try to run it on ARM A9? I am just curious about its portability thats all.

0 VENKAT47948 over 13 years ago in reply to Robert Tivy

Intellectual 610 points

Hi Robert,

We are working on DM6446 EVM board. we got linux_2.6.18 with sdk . And now we are trying to build DVSDK with new linux version downloaded from net. when we are doing this the compilation is stopping with so many errors (like undeclared symbols , no header files ) used in "cmemk.c".

I request you that, what are the changes need to be done to build DVSDK with new linux version to create "cmemk.ko,dsplink.ko".

please reply us as soon as possible .

Thanks and Regards.

0 Digant Desai over 13 years ago in reply to VENKAT47948

Expert 1225 points

I dont know whats wrong with ur setup but I could compile it even for ARM Realview Platform and run it successfully without error.

0 Robert Tivy over 13 years ago in reply to VENKAT47948

TI__Mastermind 18260 points

VENKAT47948 said:

We are working on DM6446 EVM board. we got linux_2.6.18 with sdk . And now we are trying to build DVSDK with new linux version downloaded from net. when we are doing this the compilation is stopping with so many errors (like undeclared symbols , no header files ) used in "cmemk.c".

I request you that, what are the changes need to be done to build DVSDK with new linux version to create "cmemk.ko,dsplink.ko".

CMEM supports newer kernels as well as older ones. You probably need to get a newer CMEM than what came with an SDK based on Linux 2.6.18. Here is a link to Linux Utils releases, which CMEM is a part of: http://software-dl.ti.com/dsps/dsps_public_sw/sdo_sb/targetcontent/linuxutils/index.html

Regards,

- Rob

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