Jeremy Elson wrote:
>
> Marcelo Tosatti writes:
> >On Wed, 7 Mar 2001, Alexander Viro wrote:
> >> You are reinventing the wheel.
> >> man ptrace (see PTRACE_{PEEK,POKE}{TEXT,DATA} and PTRACE_{ATTACH,CONT,DETACH})
> >
> >With ptrace data will be copied twice. As far as I understood, Jeremy
> >wants to avoid that.
>
> Yes - I've been looking at the sys_ptrace code and it seems that it
> does two copies through the kernel (but, using access_process_vm
> instead of copy_from_user -- I'm not sure how they differ). I'm
> trying to reduce the number of copies by giving one process a pointer
> into another process's address space.
I've investigated this in past to do the same thing you're trying (in my
case I was interested in a full user space implementation of OSS
emulation layer for ALSA).
The other huge drawback for ptrace is the impossibility to use mmap.
With older versions of Linux it was feasible to mmap /proc/PID/mem and
this was a very elegant way to do the job.
Unfortunately this feature has been dropped, but I don't know for which
reasons.
-- Abramo Bagnara mailto:abramo@alsa-project.orgOpera Unica Phone: +39.546.656023 Via Emilia Interna, 140 48014 Castel Bolognese (RA) - Italy
ALSA project is http://www.alsa-project.org sponsored by SuSE Linux http://www.suse.com
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This archive was generated by hypermail 2b29 : Wed Mar 07 2001 - 21:00:22 EST