* [ECOS] place thread stack into CCM memory on STM32
@ 2014-10-16 14:01 Oleg Uzenkov
2014-10-17 12:02 ` Oleg Uzenkov
0 siblings, 1 reply; 4+ messages in thread
From: Oleg Uzenkov @ 2014-10-16 14:01 UTC (permalink / raw)
To: eCos Discussion
Hi Everyone,
STM32 controllers have CCM (Closely Coupled Memory) memory which acts as
RAM.
At present I do not use it. But I would like to.
I am developing eCos application in C++. I have something like this in
the header file:
class A :
{
public:
A ();
virtual ~A ();
..
protected:
cyg_thread _thread;
char _thread_stack [CYGNUM_HAL_STACK_SIZE_TYPICAL]
__attribute__((section(".ccm")));
...
As you can see, I want to place thread stack into CCM section (using
__attribute__((section("<name>"))).
But I do not know how to do it in a correct way. Please help! :-)
The Memory layout file I use has got:
..
SECTIONS
{
SECTIONS_BEGIN
USER_SECTION (ccm, ccm, 0x10000000, LMA_EQ_VMA)
..
And cortexm.ld file has got a macro for USER_SECTION:
#define USER_SECTION(_name_, _region_, _vma_, _lma_) \
._name_ _vma_ : _lma_ \
{ __ ## _name_ ## _start = ABSOLUTE (.); \
*(._name_*) \
__ ## _name_ ## _end = ABSOLUTE (.); } \
> _region_
When I compile the project I get an error:
error: section attribute not allowed for '_thread_stack'
Do I specify attribute in the correct place?
My be I cannot do it for class members but only for global variables?
I would appreciate any help on this.
Oleg
...
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [ECOS] place thread stack into CCM memory on STM32
2014-10-16 14:01 [ECOS] place thread stack into CCM memory on STM32 Oleg Uzenkov
@ 2014-10-17 12:02 ` Oleg Uzenkov
2014-10-17 14:25 ` Sergei Gavrikov
0 siblings, 1 reply; 4+ messages in thread
From: Oleg Uzenkov @ 2014-10-17 12:02 UTC (permalink / raw)
To: eCos Discussion
>
> Hi Everyone,
>
> STM32 controllers have CCM (Closely Coupled Memory) memory which acts
> as RAM.
>
> At present I do not use it. But I would like to.
>
> I am developing eCos application in C++. I have something like this in
> the header file:
>
> class A :
> {
> public:
> A ();
> virtual ~A ();
> ..
> protected:
>
> cyg_thread _thread;
> char _thread_stack [CYGNUM_HAL_STACK_SIZE_TYPICAL]
> __attribute__((section(".ccm")));
> ...
>
> As you can see, I want to place thread stack into CCM section (using
> __attribute__((section("<name>"))).
>
> But I do not know how to do it in a correct way. Please help! :-)
>
> The Memory layout file I use has got:
>
> ..
> SECTIONS
> {
> SECTIONS_BEGIN
> USER_SECTION (ccm, ccm, 0x10000000, LMA_EQ_VMA)
> ..
>
> And cortexm.ld file has got a macro for USER_SECTION:
>
> #define USER_SECTION(_name_, _region_, _vma_, _lma_) \
> ._name_ _vma_ : _lma_ \
> { __ ## _name_ ## _start = ABSOLUTE (.); \
> *(._name_*) \
> __ ## _name_ ## _end = ABSOLUTE (.); } \
> > _region_
>
>
> When I compile the project I get an error:
> error: section attribute not allowed for '_thread_stack'
>
> Do I specify attribute in the correct place?
>
Ok, it appears that it is possible to specify
__attribute__((section("<name>"))) for class's member methods.
It can also be specified for file level or global level variables and
functions.
But unfortunately there is no directive to place the whole class into a
specific memory region.
As to working with STM32 I managed to place thread stacks into CCM
section (why waist it!) by declaring stack as a file level variable:
static char _thread_stack [CYGNUM_HAL_STACK_SIZE_TYPICAL]
CYGBLD_ATTRIB_SECTION(".ccm");
Make sure to specify (NOLOAD) for .ccm section in mlt_ file:
USER_SECTION (ccm, ccm, 0x10000000 (NOLOAD), LMA_EQ_VMA)
Otherwise the binary will be enormous.
Oleg
> My be I cannot do it for class members but only for global variables?
>
> I would appreciate any help on this.
>
> Oleg
>
>
>
>
>
>
>
> ...
>
>
>
>
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [ECOS] place thread stack into CCM memory on STM32
2014-10-17 12:02 ` Oleg Uzenkov
@ 2014-10-17 14:25 ` Sergei Gavrikov
2014-10-17 15:45 ` Sergei Gavrikov
0 siblings, 1 reply; 4+ messages in thread
From: Sergei Gavrikov @ 2014-10-17 14:25 UTC (permalink / raw)
To: Oleg Uzenkov; +Cc: eCos Discussion
On Fri, 17 Oct 2014, Oleg Uzenkov wrote:
> Ok, it appears that it is possible to specify
> __attribute__((section("<name>"))) for class's member methods.
Really?
https://gcc.gnu.org/onlinedocs/gcc/Variable-Attributes.html says
You may use the section attribute with initialized or uninitialized
global variables.
IMO, your C++ style (rejected) is not very good. Look, please, on the
eCos kernel's tests in C++ (those *.cxx tests are examples to follow).
In a fact that C++ coding style is something likes EC++. I would say it
is Embedded C++ style from eCos gurus.
Find kernel/current/tests/testaux.hxx and tests/*.cxx code.
On 64K aside. I would try to "move" eCos heap (__heap1) in .ccm segment.
Then all dynamic stuff will be live in .ccm segment. Benefits: 1) you
will get more space for eCos program (code+data) ~120K; 2) you will get
64K room for all dynamically allocated objects (just allocate the
buffers for thread's stacks); 3) no mess with 'section' attribute.
Drawback(s): 1) if you won't use 'new' or 'malloc' (will you?) then .ccm
will be waste. I seems for me (not tested, I have no STM target) you have
only to re-define the heap's size in mlt*h (set it 64K) and move __heap1
label in mlt*ldi (put __heap1 after .ccm section). Well, this is just an
idea, perhaps, I miss something and it will not work, but you can try
it.
Sergei
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^ permalink raw reply [flat|nested] 4+ messages in thread
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2014-10-16 14:01 [ECOS] place thread stack into CCM memory on STM32 Oleg Uzenkov
2014-10-17 12:02 ` Oleg Uzenkov
2014-10-17 14:25 ` Sergei Gavrikov
2014-10-17 15:45 ` Sergei Gavrikov
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