Debugging gem5: BrokenPipeError

[zhaorui233]

I follow the book chapter 'Debugging gem5'
run cmd : build/X86/gem5.opt --debug-flags=Exec configs/learning_gem5/part1/simple.py | head -n 50
shows:
Global frequency set at 1000000000000 ticks per second
warn: No dot file generated. Please install pydot to generate the dot file and pdf.
src/mem/dram_interface.cc:690: warn: DRAM device capacity (8192 Mbytes) does not match the address range assigned (512 Mbytes)
src/base/statistics.hh:279: warn: One of the stats is a legacy stat. Legacy stat is a stat that does not belong to any statistics::Group. Legacy stat is deprecated.
system.remote_gdb: Listening for connections on port 7000
src/sim/simulate.cc:194: info: Entering event queue @ 0. Starting simulation...
gem5 Simulator System. https://www.gem5.org
gem5 is copyrighted software; use the --copyright option for details.

gem5 version 23.0.1.0
gem5 compiled Aug 24 2023 15:14:23
gem5 started Aug 24 2023 15:18:10
gem5 executing on dell-workstation, pid 68707
command line: build/X86/gem5.opt --debug-flags=Exec configs/learning_gem5/part1/simple.py

Beginning simulation!
77000: system.cpu: T0 : 0x400190 @_start : xor rbp
77000: system.cpu: T0 : 0x400190 @_start. 0 : XOR_R_R : xor rbp, rbp, rbp : IntAlu : D=0x0000000000000000
126000: system.cpu: T0 : 0x400193 @_start+3 : mov rdx
126000: system.cpu: T0 : 0x400193 @_start+3. 0 : MOV_R_R : mov r9, r9, rdx : IntAlu : D=0x0000000000000000
175000: system.cpu: T0 : 0x400196 @_start+6 : pop rsi
175000: system.cpu: T0 : 0x400196 @_start+6. 0 : POP_R : ld t1, SS:[t0 + rsp] : MemRead : D=0x0000000000000001 A=0x7fffffffed90
238000: system.cpu: T0 : 0x400196 @_start+6. 1 : POP_R : addi rsp, rsp, 0x8 : IntAlu : D=0x00007fffffffed98
238000: system.cpu: T0 : 0x400196 @_start+6. 2 : POP_R : mov rsi, rsi, t1 : IntAlu : D=0x0000000000000001
336000: system.cpu: T0 : 0x400197 @_start+7 : mov rsp
336000: system.cpu: T0 : 0x400197 @_start+7. 0 : MOV_R_R : mov rdx, rdx, rsp : IntAlu : D=0x00007fffffffed98
385000: system.cpu: T0 : 0x40019a @_start+10 : and rsp, 0xfffffffffffffff0
385000: system.cpu: T0 : 0x40019a @_start+10. 0 : AND_R_I : limm t1, 0xfffffffffffffff0 : IntAlu : D=0xfffffffffffffff0
385000: system.cpu: T0 : 0x40019a @_start+10. 1 : AND_R_I : and rsp, rsp, t1 : IntAlu : D=0x0000000000000000
434000: system.cpu: T0 : 0x40019e @_start+14 : push rax
434000: system.cpu: T0 : 0x40019e @_start+14. 0 : PUSH_R : st rax, SS:[t0 + rsp + 0xfffffffffffffff8] : MemWrite : D=0x0000000000000000 A=0x7fffffffed88
455000: system.cpu: T0 : 0x40019e @_start+14. 1 : PUSH_R : subi rsp, rsp, 0x8 : IntAlu : D=0x00007fffffffed88
504000: system.cpu: T0 : 0x40019f @_start+15 : push rsp
504000: system.cpu: T0 : 0x40019f @_start+15. 0 : PUSH_R : st rsp, SS:[t0 + rsp + 0xfffffffffffffff8] : MemWrite : D=0x00007fffffffed88 A=0x7fffffffed80
525000: system.cpu: T0 : 0x40019f @_start+15. 1 : PUSH_R : subi rsp, rsp, 0x8 : IntAlu : D=0x00007fffffffed80
574000: system.cpu: T0 : 0x4001a0 @_start+16 : mov r15, 0x40a060
574000: system.cpu: T0 : 0x4001a0 @_start+16. 0 : MOV_R_I : limm r8, 0x40a060 : IntAlu : D=0x000000000040a060
672000: system.cpu: T0 : 0x4001a7 @_start+23 : mov rdi, 0x409ff0
672000: system.cpu: T0 : 0x4001a7 @_start+23. 0 : MOV_R_I : limm rcx, 0x409ff0 : IntAlu : D=0x0000000000409ff0
770000: system.cpu: T0 : 0x4001ae @_start+30 : mov rdi, 0x400274
770000: system.cpu: T0 : 0x4001ae @_start+30. 0 : MOV_R_I : limm rdi, 0x400274 : IntAlu : D=0x0000000000400274
868000: system.cpu: T0 : 0x4001b5 @_start+37 : call 0x9846
868000: system.cpu: T0 : 0x4001b5 @_start+37. 0 : CALL_NEAR_I : limm t1, 0x9846 : IntAlu : D=0x0000000000009846
868000: system.cpu: T0 : 0x4001b5 @_start+37. 1 : CALL_NEAR_I : rdip t7, t7 : IntAlu : D=0x00000000004001ba
868000: system.cpu: T0 : 0x4001b5 @_start+37. 2 : CALL_NEAR_I : st t7, SS:[rsp + 0xfffffffffffffff8] : MemWrite : D=0x00000000004001ba A=0x7fffffffed78
889000: system.cpu: T0 : 0x4001b5 @_start+37. 3 : CALL_NEAR_I : subi rsp, rsp, 0x8 : IntAlu : D=0x00007fffffffed78
889000: system.cpu: T0 : 0x4001b5 @_start+37. 4 : CALL_NEAR_I : wrip t7, t1 : IntAlu :
952000: system.cpu: T0 : 0x409a00 @__libc_start_main : push r15
952000: system.cpu: T0 : 0x409a00 @__libc_start_main. 0 : PUSH_R : st r15, SS:[t0 + rsp + 0xfffffffffffffff8] : MemWrite : D=0x0000000000000000 A=0x7fffffffed70
973000: system.cpu: T0 : 0x409a00 @__libc_start_main. 1 : PUSH_R : subi rsp, rsp, 0x8 : IntAlu : D=0x00007fffffffed70
1022000: system.cpu: T0 : 0x409a02 @__libc_start_main+2 : movsxd rax
1022000: system.cpu: T0 : 0x409a02 @__libc_start_main+2. 0 : MOVSXD_R_R : sexti rax, rsi, 0x1f : IntAlu : D=0x0000000000000001
1071000: system.cpu: T0 : 0x409a05 @__libc_start_main+5 : mov r9
1071000: system.cpu: T0 : 0x409a05 @__libc_start_main+5. 0 : MOV_R_R : mov r15, r15, r9 : IntAlu : D=0x0000000000000000
1120000: system.cpu: T0 : 0x409a08 @__libc_start_main+8 : push r14
Exception ignored in: <_io.TextIOWrapper name='' mode='w' encoding='ascii'>
BrokenPipeError: [Errno 32] Broken pipe

how to solve this error ?

[abmerop]

Remove the pipe to head -n 50. The error is Linux telling you the pipe'd process (gem5) is exiting because the program receiving the output ended and also why there are exactly 50 lines of output

[zhaorui233]

How to remove the pipe ? Should I use some commands or write a script ?

[BobbyRBruce]

The command you ran was build/X86/gem5.opt --debug-flags=Exec configs/learning_gem5/part1/simple.py | head -n 50. The | is the "pipe". It sends the output of build/X86/gem5.opt --debug-flags=Exec configs/learning_gem5/part1/simple.py to the head application with the arguments -n 50. head -n 50 will output the first 50 lines it gets then stop. When this stop occurs gem5 crashes as it's got nowhere left to output to.

So, all you need to do is execute build/X86/gem5.opt --debug-flags=Exec configs/learning_gem5/part1/simple.py (i.e., without the trailing | head -n 50).

[zhaorui233]

Thanks for replying. It works now.