add more debug info in gdb,the result is at bellow. my kernel is 64bit,is this the reason? #sudo modprobe -r gtp #sudo modprobe gtp #sudo /work/kgtp/gdb/gdb/gdb vmlinux GNU gdb (GDB) 7.2.50.20101216-cvs Copyright (C) 2010 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "--host=mipsel-unknown-linux-gnu --target=mipsel-linux". For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>... Reading symbols from /work/rt4ls/vmlinux...done. (gdb) target remote /proc/gtp Remote debugging using /proc/gtp sending: "qSupported:qRelocInsn+" received: "ConditionalTracepoints+;TracepointSource+;DisconnectedTracing+" sending: "Hg0" received: "" sending: "?" received: "S05" sending: "Hc-1" received: "" sending: "qC" received: "" sending: "qAttached" received: "" sending: "qOffsets" received: "" sending: "Hg0" received: "" sending: "g" received: "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" sending: "g" received: "00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000" sending: "m0,4" received: "E0e" sending: "mfffffffffffffffc,4" received: "E0e" sending: "m0,4" received: "E0e" 0x0000000000000000 in ?? () sending: "qSymbol::" received: "" sending: "qTStatus" received: "T0;tnotrun:0;tframes:0;tcreated:0;tsize:500000;tfree:500000;circular:0;disconn:0" remote_get_noisy_reply(): T0;tnotrun:0;tframes:0;tcreated:0;tsize:500000;tfree:500000;circular:0;disconn:0 sending: "qTfV" received: "1:0:1:63757272656e745f7461736b" sending: "qTsV" received: "l" sending: "qTfP" received: "l" (gdb) trace sys_read sending: "mffffffff802f4f94,4" received: "00200400" Tracepoint 1 at 0xffffffff802f4f94: file fs/read_write.c, line 373. (gdb) actions Enter actions for tracepoint 1, one per line. End with a line saying just "end". >collect $reg >end (gdb) tstart sending: "QTinit" received: "OK" remote_get_noisy_reply(): OK sending: "QTDP:1:ffffffff802f4f94:E:0:0-" received: "OK" remote_get_noisy_reply(): OK sending: "QTDP:-1:ffffffff802f4f94:R03FFFFFFFFFFFFFFFFFFFFFF" received: "OK" remote_get_noisy_reply(): OK sending: "QTDPsrc:1:ffffffff802f4f94:at:0:8:7379735f72656164" received: "OK" remote_get_noisy_reply(): OK sending: "QTDPsrc:1:ffffffff802f4f94:cmd:0:c:636f6c6c6563742024726567" received: "OK" remote_get_noisy_reply(): OK sending: "QTDV:1:0000000000000000:1:63757272656e745f7461736b" received: "OK" remote_get_noisy_reply(): OK sending: "QTro:ffffffff80200000,ffffffff80741710:ffffffff80741710,ffffffff80748e30:ffffffff80748e30,ffffffff80748e54:ffffffff80749000,ffffffff80844500:ffffffff80844500,ffffffff808452a0:ffffffff808452a0,ffffffff808502d0:ffffffff808502d0,ffffffff80855610:ffffffff80855610,ffffffff8085ae28:ffffffff8085ae28,ffffffff8085d7c8:ffffffff8085d7c8,ffffffff8086f838:ffffffff8086f838,ffffffff80872000:ffffffff808c8000,ffffffff80908990:ffffffff80914200,ffffffff80916880" received: "OK" sending: "QTDisconnected:0" received: "OK" remote_get_noisy_reply(): OK sending: "QTBuffer:circular:0" received: "OK" remote_get_noisy_reply(): OK sending: "QTStart" received: "E16" remote_get_noisy_reply(): E16 remote.c: error in outgoing packet at field #6. (gdb) quit A debugging session is active. Inferior 1 [Remote target] will be killed. Quit anyway? (y or n) sending: "qTStatus" received: "T0;tstop:0;tframes:0;tcreated:0;tsize:500000;tfree:500000;circular:0;disconn:0" remote_get_noisy_reply(): T0;tstop:0;tframes:0;tcreated:0;tsize:500000;tfree:500000;circular:0;disconn:0 sending: "k"