enabling/disabling trampoline

Cristiano Ligieri Pereira pereirac at uci.edu
Mon Mar 10 08:33:06 CET 2003

Hi all,

I understand that the trampoline mechanism slows down the execution
because it adds one more level of "indirection" when handling system calls
on l4-linux. I would like to run some experiments with/without it but I'm
not quite sure on how to achieve it,i.e., disable and enable it back
again. Do I have to recompile the whole kernel? Do I have to recompile
only the Linux application I will run on the top of l4-linux? What exactly
do I have to do?

I'm pasting part of a message from mailing list in which Frank Mehnert
mention something about a patch, which I could not find.

Any help is appreciated.

> Additional speedup for L4Linux could be achieved by patching the
> syscalls in the libc by direct jumping into the emulib of the process
> preventing the trampoline mechanism (int 0x80 => general protection =>
> int 0x30 => l4linux server). I don't know if such a patch if floating
> around somewhere. See linux22/arch/l4/x86/emulib/int_entry.S, function
> entry13.

Cristiano Ligieri Pereira - http://www.ics.uci.edu/~cpereira

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