Problem with hybrid L4Linux task

Frank Mehnert fm3 at
Mon Sep 19 18:47:30 CEST 2005

Hi Mathias,

On Monday 19 September 2005 18:37, Mathias Krause wrote:
> Here the server already deregisters itself at names because he got a
> message with an empty buffer => means "end of transmition".
> | ...
> | +++>  26.00 recv dope=00004000 (OK) 27.00 (00000000,00000000)   3966
> | ipc:  26.00 recv from 27.00 TO=INF                              3965
> | ...
> Here the server starts waiting for the client to send data in a buffer
> sized 4k.

4k direct IPC or indirect IPC? What message 27.00 send to 26.00 (events
before 3965)? It seems that 27.00 did only send a short message containing
two dwords.

> > Maybe the compiler optimizes some code away. I assume that you tried the
> > last version of L4Linux 2.6 -- Adam changed many things to get hybrid
> > tasks working.
> It's a version a week old or so. It was very stable at this time (no
> changes in CVS for some time).

Ok, right.

> > We cannot guarantee that the bindings are bug-free but they have been
> > tested for a long time. Do you use any special compiler switches besides
> > -O2? Do you use -fomit-frame-pointer? Try without. Do you use -fstrict-
> > aliasing? Try with -fno-strict-aliasing as defined in l4/mk/
> My CFLAGS are '-W -Wall -g -O2', so this should be ok, doesn't it?

You should also add -fno-strict-aliasing. See the appropriate documentation
of that option. I assume that you use DICE, and with DICE you _must_ use
this option so far (Ron is about to change the whole DICE compiler but that
takes much time).

> BTW, I haven't found any library containing a l4_ipc_whatever() function.
> Are the assembler inlines the only way to make ipc calls?

Yes. Therefore, L4 sources should not be compiled using -O0 or -fno-inline.
Hmm, until now we did not need to compile with -O0.

## Dept. of Computer Science, Dresden University of Technology, Germany ##
##                                     ##
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