l4linux question

Adam Lackorzynski adam at os.inf.tu-dresden.de
Sat Jun 4 02:58:13 CEST 2005


On Fri Jun 03, 2005 at 14:54:20 -0400, Andrew Davenport wrote:
> I have a fiasco l4/l4linux system setup.  I want to eventually log all linux
> system calls from within the fiasco kernel (via thread::sys_ipc and
> thread::shortcut_ipc).  I am curious: How does a linux system call get
> translated into an l4 ipc ?

On Linux and x86 a system call is done via "int $0x80". Executing this
on L4 triggers an exception that is reflected back to userland. There
are two exception models in Fiasco, L4Linux2.6 uses the exception IPC
one, i.e. the kernel generates an IPC similar to pagefault IPC that is
sent to the Linux server.
In the kernel there's a function snd_exception() that is called from the
trap handler. This function generates an IPC to the handler and waits
for a reply to resume the faulted thread (with some new state).

Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/

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