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 ... -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
> > 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
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 -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
On Fri, 17 Oct 2014, Sergei Gavrikov wrote: > 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. Excuse too hasty response. It seemed for me you managed relocation that _thread_stack[] and I cited FM on variable attributes. Sergei -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss