[okl4-developer] Question about memsection_create_fixed, iguana server library

[Nelson Tam]

Hi Anand,

On 11/04/2008, at 2:49 PM, Anand Gore wrote:
> I wanted to dynamically load a binary to a specific location e.g.
>
> 0x2000000 in my task/thread. Here is the code I have -
>
> mnsigned int base_address=0x200000;
>
> mm_s memsection_create_fixed(section_size, base_address); if(mm_s !=  
> 0) {
>
>         memcpy(base_address, binary_buffer, sizeof(binary_buffer));
>
>         func=(func_t)base_address;
>
>         func();
>
> }
>
> The binary is built and linked to a fixed address 0x2000000, such  
> that there will be an initialization function at 0x2000000.
>
> But I read in the document that the memsection_create_fixed is going  
> to go away sometime down the line.
>
> I am wondering if there is going to be a replacement function for  
> that or there is a better way to do this.
>
There certainly will be, in fact, there already is.  Here's how:

1. Compile OKL4 as normal, and find the file build/images/weaver.xml

2. Find the <physical_memory> elements.  Is 0x2000000 contained in the  
regions?  If not, add a new <physical_memory> element with <region  
base="0x2000000" size=[hex value of section_size] />.

3. Find the <physical_pool> elements.  Create a new pool:

<physical_pool name="my_binary_pool">
    <memory base="0x2000000" size=[hex value of section_size] />
</physical_pool>

4. Find the <program> XML element that contains the thread that you  
want to give the binary to.

<program ...>
    <memsection name="my_binary" file="/path/to/binary"  
phys_addr="0x2000000" physpool="my_binary_pool">
</program>

This is neat, because this even copies the contents of /path/to/binary  
to 0x2000000 physical.  Two things to beware of - the binary must fit  
into section_size; and the binary is copied into the region verbatim  
(wouldn't work if it is an ELF file).

The memsection will be created, mapped, and its contents initialised  
before any user threads are executed.

During runtime, the thread may obtain the reference to the fixed  
memsection by doing:

  binary_ms = env_memsection(iguana_getenv("MY_BINARY")); /* note  
upper case */

Hope this helps!  Please let us know if you run into any obstacles.
--
(nt)

Nelson Tam

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