2008-03-17 21:37:15 code in L1 on BF532

David Rowe (AUSTRALIA)

Message: 52621 Hi,

I just tried to move a kernel module function to L1:

int16_t echo_can_update(echo_can_state_t *ec, int16_t tx, int16_t rx)__attribute__((l1_text));

The module builds OK however when I insmod it I get:

root:/root> insmod oslec.ko

insmod: cannot insert 'oslec.ko': Operation not permitted (-1): Operation not permitted

When I remove the l1_text attribute it loads OK.

Is this attribute supported on the BF532? Perhaps there is another (say linker) option I need? It's really just this one function I want in L1.

In the boot sequence it looks like there is plenty of L1 instruction memory available:

<snip>

Blackfin Scratchpad data SRAM: 4 KB

Blackfin Instruction SRAM: 32 KB

<snip>

Aslo, I can see that the kernel is actually using some L1 (by examining /proc/kallsyms).

The function I wish to put into L1 is about 1k long and the kernel funcs in L1 are only using about 7k of the 32k available.

Thanks,

David

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2008-03-17 21:57:29 Re: code in L1 on BF532

Mike Frysinger (UNITED STATES)

Message: 52622 there is no variant-specific logic with attribute handling, nor are there special flags you need ... if the module is being rejected, it's for a different reason

look at /proc/sram to see how the L1 is being allocated

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2008-03-18 00:04:43 Re: code in L1 on BF532

David Rowe (AUSTRALIA)

Message: 52627 I think I found the reason, (at least in uClinux-dist-2007R1.1-RC3) around line 400 of linux-2.6.x/arch/blackfin/m,/blackfin_sram.c:

This:

void *l1_inst_sram_alloc(size_t size)

{

#if L1_DATA_A_LENGTH != 0

Should be:

void *l1_inst_sram_alloc(size_t size)

{

#if L1_CODE_LENGTH != 0

On the BF532 there is no L1 SRAM available but 32kb of L1 instruction memory available. When I made this mod to the kernel I could happily load functions into L1 instruction memory on the BF532, e.g. the test program from the blackfin docs site:

root:/tmp> insmod hello.ko

========Load module into L1 memory========

Code test: code function addr = 0xffa0a0f0

Cheers,

David

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2008-03-18 06:57:44 Re: code in L1 on BF532

Mike Frysinger (UNITED STATES)

Message: 52680 ah, ok ... i just checked at that has been fixed at some point between 2007R1.1 and 2008R1, so newer releases should be OK