[ECOS] POSIX main thread

Sergei Gavrikov sergei.gavrikov@gmail.com
Sun Apr 12 18:39:00 GMT 2009

Please, stop a top posting: http://en.wikipedia.org/wiki/Top_posting
Here use: http://en.wikipedia.org/wiki/Top_posting#Bottom-posting

On Sun, Apr 12, 2009 at 05:21:49PM +0200, Szentirmai Gergely wrote:
> Hello
> POSIX compatibility, not Linux compat. I'm not using the command line  
> ecos config, rather than the configtool GUI. In the ISO C startup  

Szentirmai, I belive in that what anyone can do the same using eCos GUI
(configtool) what anybody did get with `ecosconfig'. eCos documentation
talks about.

I did show you in previous post that eCos FS_FAT is not depend on POSIX
package. It requires CYGPKG_BLOCK_LIB package and this package depends
on CYGPKG_LINUX_COMPAT (I guess on some compatible headers).

> section, I have found abelity to define the calling mode of main(), and  
> the default stacksize. My coniguration is to call main() from  
> cyg_user_start context. This way ecos does not allocate stack for  
> starting main. This way, the

Is it so exactly? eCos iself stands up the main() thread (it is declared
as a weak function). By default, it does nothing (returns immediately),
if do not have own one. Even more, you can remove an eCos package
CYGPKG_ISO_STARTUP from your configuration. Try to remove it. As I could
understand you try to reduce any overhead from eCos+fatfs.

Just to demo (without the STACK_SIZE dances). I will use stm3210e target
to finalize example: eCos+fatfs-main ("minus main"). Once again, I
belive in that what you will be able to get it with `configtool' too
(see what I add and see what I remove and do the same using GUI).

$ ecosconfig new stm3210e default
$ ecosconfig add crc fileio CYGPKG_BLOCK_LIB CYGPKG_LINUX_COMPAT fatfs
U CYGBLD_ISO_FNMATCH_HEADER, new inferred value <cyg/fileio/fnmatch.h>
U CYGBLD_ISO_DIRENT_HEADER, new inferred value <cyg/fileio/dirent.h>
U CYGBLD_ISO_OPEN_MAX_HEADER, new inferred value <cyg/fileio/limits.h>
U CYGBLD_ISO_NAME_MAX_HEADER, new inferred value <cyg/fileio/limits.h>
$ ecosconfig remove CYGPKG_LIBC_STARTUP
$ ecosconfig check
Target: stm3210e_eval
Template: default
No conflicts


$ make -s -C fs/fat/v3_0 tests
$ arm-eabi-size install/tests/fs/fat/v3_0/tests/fatfs1
    text   data	    bss	    dec	    hex	filename
  34052	    944	   6276	  41272	   a138	install/tests/fs/fat/v3_0/tests/fatfs1

I checked that there are a lot of fatfs entries in the executable (it's
too long list to paste here)

$ arm-eabi-nm install/tests/fs/fat/v3_0/tests/fatfs1 | grep fatfs
6800a734 T fatfs_write_data
6800b1fc T fatfs_write_dir_entry

$ arm-eabi-nm install/tests/fs/fat/v3_0/tests/fatfs1 | grep fatfs | wc -l

As you can see it was possible to get eCos+fatfs-main with an unbeat
size. Try to get it with `configtool'. You have to get something I have
got. There are menus to add/remove packages in `configtool'. And, it
seems for me that you must read eCos documentation. For reference about
ISO main() startup read eCos reference:


> CYGNUM_LIBC_MAIN_DEFAULT_STACK_SIZE   option is disabled. So, I can't set 
> the value (in the GUI of course). 
> When I use POSIX layer, pthread.cxx allocates a stack whether there is a  
> main() function, or not. The size of this stack is depending on  
> PTHREAD_STACK_MINIMUM is given, but I think  
> CYGNUM_LIBC_MAIN_DEFAULT_STACK_SIZE  should be active even if there is a  
> POSIX compatibility layer added.
> Thank you!
> Gergely Szentirmai
> Sergei Gavrikov írta:
>> On Fri, Apr 10, 2009 at 08:03:29PM +0200, Szentirmai Gergely wrote:
>>> Hello
>>> I had to add POSIX compatibility to my project, because FAT support 
>>> is  depending on it. It's ok, but I don't need POSIX compat to create 
>>> a  thread, and call main(). It eats 8k from my SRAM, and that hurts 
>>> much!
>> Hm. POSIX compat or LINUX compat? It's possible do not include posix
>> package to buid eCos `fatfs1' test
>> ecosconfig new <target>
>> ecosconfig add CYGPKG_LINUX_COMPAT
>> ecosconfig add CYGPKG_BLOCK_LIB
>> ecosconfig add fileio fatfs
>> ecosconfig tree
>> make -s
>> make -s -C fs/fat/current/ tests
>> The fatfs1's size is
>> arm-eabi-size install/tests/fs/fat/current/tests/fatfs1    text	   
>> data	    bss	    dec	    hex	filename
>>   48088	    956	  15148	  64192	   fac0	install/tests/fs/fat/current/tests/fatfs1
>>> As I see from the source pthread.cxx there is no upportunitiy to 
>>> disable  this feature.
>>> Would not be it usefull? Or there is a reason, why it is not 
>>> available.  As a secound option, I would make a 
>>> main_thread_stack_size option in  posix thread configuration in the 
>>> cdl.
>> If your main() will be just a paleholder, decrease it's stack. If you
>> import the below, for example, before to type 'ecosconfig tree'
>>     user_value 128;
>> };
>> you will decrease .bss. It's just an example! Unfortunately, AFAIK,
>> FATFS will suck in any case, you can think, I will decrease .bss, and
>> all will be okay, but FATFS sucks a heap too
>> arm-eabi-nm install/tests/fs/fat/current/tests/fatfs1 | grep alloc
>>            ...
>> 68010aa4 T cyg_fd_alloc
>> 68010b1c T cyg_file_alloc
>> 68013dd0 D cygmem_memalloc_heaps
>> 6800cc94 T fatfs_node_alloc
>> 6800f9d0 T malloc
>> Yet another "reserve" to decrease amount of used RAM is to decrease
>> Sergei

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