Hi Philippe, this appears to be related to 2.6.22+ only: ------------[ cut here ]------------ kernel BUG at fs/buffer.c:1230! invalid opcode: 0000 [#1] PREEMPT Modules linked in: xeno_rtdm xeno_nucleus ip6t_LOG xt_TCPMSS nvram uinput snd_pcm_oss cifs snd_mixer_oss snd_seq snd_seq_device radeon drm wlan_tkip af_packet thinkpad_acpi button battery ac ip6t_REJECT xt_state iptable_nat nf_nat ip6table_mangle nf_conntrack_ipv4 nf_conntrack nfnetlink ip6table_filter ip6_tables ipv6 nls_iso8859_1 nls_cp437 vfat fat nls_utf8 ntfs dm_mod fuse wlan_scan_sta ath_rate_sample pcmcia snd_intel8x0 firmware_class snd_ac97_codec ac97_bus snd_pcm ath_pci nsc_ircc wlan ide_cd irda snd_timer e100 cdrom ath_hal(P) snd i2c_i801 uhci_hcd ehci_hcd mii yenta_socket rsrc_nonstatic soundcore usbcore snd_page_alloc i2c_core intel_agp crc_ccitt pcmcia_core agpgart parport_pc lp parport reiserfs edd fan piix ide_disk ide_core CPU: 0 EIP: 0060:[] Tainted: P VLI EFLAGS: 00210246 (2.6.22.2-adeos #7) EIP is at __find_get_block+0x2c/0x1e8 eax: 00000000 ebx: e3635dac ecx: 00000000 edx: 00002e4e esi: 00001000 edi: eeeb3080 ebp: e3635b30 esp: e3635af8 ds: 007b es: 007b fs: 0000 gs: 0033 ss: 0068 Process kio_file (pid: 7433, ti=e3634000 task=e6d780b0 task.ti=e3634000)<0> I-pipe domain Linux Stack: 00002e4e 00000000 c16e0718 eff36a90 e3634000 e3635b1c c0308f1e c05dd700 00000000 e3635b2c c030bbfd e3635dac 00001000 e3635db4 e3635b98 c01881a4 00001000 c05dd700 511c5a51 00000022 c014aade 00002e4e 00000000 eeeb3080 Call Trace: [] show_trace_log_lvl+0x1f/0x34 [] show_stack_log_lvl+0xa0/0xa8 [] show_registers+0x207/0x35c [] die+0x114/0x22a [] do_trap+0x8e/0xa7 [] do_invalid_op+0x8d/0x97 [] __ipipe_handle_exception+0xb1/0x11f [] error_code+0x6f/0x7c [] __getblk+0x25/0x29a [] search_by_key+0x97/0xe38 [reiserfs] [] search_by_entry_key+0x20/0x231 [reiserfs] [] reiserfs_find_entry+0x75/0x2d0 [reiserfs] [] reiserfs_lookup+0x6d/0x122 [reiserfs] ... I get this over 2.6.22.2 with latest trunk + ipipe-1.9-03, only modprobe'ing xeno_rtdm (so that the nucleus becomes active) and then logging into KDE. Same box, same Xenomai, but 2.6.20.15: no problem at all (also xeno-text runs fine here, BTW). When Xenomai is inactive, 2.6.22 makes no problems as well. Note that the tracer is compiled in, but is deactivated. Activating it (with the hope to get a panic backtrace) makes the issue disappear as well. Jan