[okl4-developer] Wombat Linux User applications making Linux syscall

[Stefan Kalkowski]

Hi Jithu,

AFAIK, the code to handle the IPC from the wombat syscall thread is 
in 'arch/l4/sys-XXX/user.S' and gets mapped to some fixed ('TASK_SIG_BASE') 
address in the Linux user task. The mapping is done in a lazy fashion, have a 
look at the pagefault handling code in function 'l4_do_page_fault' 
('arch/l4/kernel/syscall_loop.c').
Probably the first time the application is scheduled its eip is set to that 
special page, so that the signal handling code becomes available.

regards stefan

PS: Btw. I use Oklinux version 2.6.23.24.

On Tuesday, 12. January 2010 12:09:08 jithu joseph wrote:
> Hi all,
>
> I understand that when a  wombat user process compiled
> independently[from the okl4/ iguana build system], makes a linux
> system call
> 1.  a software interrupt is generated and L4 microkernel process it
> 2. it notifies the wombat syscall thread via IPC
> 3.  wombat syscall thread notifies the user process via IPC
>
> Step 3 implies that some code is inserted [by the tool chain] which
> processes this IPC. Can someone clarify / contradict this observation
> ?
>
> So where does the IPC handling code gets inserted into the user process ?
>
>
> Thanks and Regards
> Jithu
>
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-- 
Stefan Kalkowski
Genode Labs Developer
http://genode-labs.com