Hi all, Back at home I have done some experiments (Sorry for the long post !!) Since I was using qjackctl to launch jack I did not notice that the error message "cannot lock down memory for RT thread (Operation not permitted)" was not a jackd message but a message from qjackctl when it try to connect to the jack server. As root everything work fine. When running jackstart as normal user I get : --cut here-- [christophe@localhost christophe]$ jackstart -R -v -d alsa -d hw:0 -p 1024 back from read, ret = 1 errno == Success jackd 0.80.0 Copyright 2001-2003 Paul Davis and others. jackd comes with ABSOLUTELY NO WARRANTY This is free software, and you are welcome to redistribute it under certain conditions; see the file COPYING for details 3701 waiting for signals JACK compiled with System V SHM support capabilities: =i cap_setpcap,cap_ipc_lock,cap_sys_nice,cap_sys_resource+ep loading driver .. new client: alsa_pcm, id = 1 type 1 @ 0x805ac70 fd = -1 creating alsa driver ... hw:0|hw:0|1024|2|48000|nomon|swmeter|rt open registered port alsa_pcm:capture_1, offset = 4096 registered port alsa_pcm:capture_2, offset = 8192 registered port alsa_pcm:playback_1, offset = 0 registered port alsa_pcm:playback_2, offset = 0 ++ jack_rechain_graph(): client alsa_pcm: internal client, execution_order=0. -- jack_rechain_graph() starting engine load = 0.0586 max usecs: 25.000, spare = 21308.000 load = 0.0715 max usecs: 18.000, spare = 21315.000 load = 0.0850 max usecs: 21.000, spare = 21312.000 --cut here-- So it seems ok, capabilities are enable,I start ams synth with "ams --jack" still ok but when I try to connect ams_synth to alsa : --cut here-- [christophe@localhost christophe]$ jack_connect ams_128_0:Out_ID1_0 alsa_pcm:playback_1 engine sample rate: 48000 cannot lock down memory for RT thread (Operation not permitted) cannot activate client --cut here-- The output of the jack terminal during the connection is : -- cut here -- registered port ams_128_0:Out_ID1_0, offset = 12288 registered port ams_128_0:Out_ID1_1, offset = 16384 new client: jack_connect, id = 4 type 2 @ 0x411ff000 fd = 14 removing failed client jack_connect state = Not triggered errors = 0 adios senor jack_connect *&*&*&*&** senor jack_connect - you are a ZOMBIE ++ jack_rechain_graph(): client alsa_pcm: internal client, execution_order=0. -- jack_rechain_graph() -- cut here -- my /etc/fstab is -- cut here -- /dev/hda6 / ext3 defaults 1 1 none /dev/pts devpts mode=0620 0 0 /dev/hda9 /home ext3 defaults 1 2 none /mnt/cdrom supermount dev=/dev/scd0,fs=auto,ro,--,iocharset=iso8859-15,codepage=850,umask=0 0 0 none /mnt/floppy supermount dev=/dev/fd0,fs=auto,--,iocharset=iso8859-15,sync,codepage=850,umask=0 0 0 /dev/hda1 /mnt/win_c vfat iocharset=iso8859-15,codepage=850,umask=0 0 0 /dev/hda5 /mnt/win_d vfat iocharset=iso8859-15,codepage=850,umask=0 0 0 none /proc proc defaults 0 0 /dev/hda8 /usr ext3 defaults 1 2 /dev/hda7 swap swap defaults 0 0 shmfs /dev/shm shm defaults 0 0 none /mnt/ramfs tmpfs defaults 0 0 none /tmp/jack tmpfs defaults 0 0 -- cut here -- If it work as root it should not be a problem of memory !! So I think it may be a problem with the jack tmp files. jackstart creates 4 tmp files with my user name : ls -l /tmp -- cut here -- drwxrwxrwx 1 root root 0 sep 6 13:59 jack/ srwxr-xr-x 1 christophe christophe 0 sep 6 15:30 jack_0= srwxr-xr-x 1 christophe christophe 0 sep 6 15:30 jack_ack_0= prw-r--r-- 1 christophe christophe 0 sep 6 15:30 jack-ack-fifo-4187-0| prw-r--r-- 1 christophe christophe 0 sep 6 15:30 jack-ack-fifo-4187-1| -- cut here -- jackd as root does the same but the owner of the tmp files is root of course. Well will work as root for the moment !! Regards, Christophe