[lldb-dev] How can lldb debug a remote bare-metal platform?

Tue Sep 19 11:21:10 PDT 2017

Hello,

‘target modules load -lp’  fails with error “one or more section name + load address pair must be specified”, works only with --slide option.

Another issue is that if breakpoint is set, Process::WriteMemory  return zero and ObjectFile::LoadInMemory interprets it as an error without setting appropriate status. Thus, user sees nothing in output as if command succeeds.

Thanks,
Tatyana

From: lldb-dev [mailto:lldb-dev-bounces at lists.llvm.org] On Behalf Of Greg Clayton via lldb-dev
Sent: Tuesday, 19 September, 2017 6:06 PM
To: cui bixiong <cuibixiong at gmail.com>
Cc: lldb-dev at lists.llvm.org
Subject: Re: [lldb-dev] How can lldb debug a remote bare-metal platform?

Load like "target modules load" has a --load option that will load the ELF into memory. I think it should do what you want. Let me know how it goes.

Greg Clayton

On Sep 18, 2017, at 9:58 PM, cui bixiong <cuibixiong at gmail.com<mailto:cuibixiong at gmail.com>> wrote:

Hi Greg:

    It's worked, thank you!, but I still have a question, in GNU-GDB which provide `load` command to download a ELF file into bare-board, in LLDB support those features? should I dump a binary file and use lldb "target module load" to replace 'load' command?

Best Regards
--cuibixiong

2017-09-18 23:53 GMT+08:00 Greg Clayton <clayborg at gmail.com<mailto:clayborg at gmail.com>>:
So when launching a GDB server there are two flows:

1 - When you connect you already have a process
2 - You will connect, then launch or attach to a process

LLDB tries to see if there is a process by sending the "qfThreadInfo" packet. As you see below, it responds with on character "l" which means  "end of the thread list". Since no thread IDs were returned, this makes LLDB believe that there is no process on the other end. So later when you try to say "process launch", it tries to send the "A" packet which tries to launch your program by sending the name of the process file to launch.

There was recently an OpenOCD patch to work around this with:

https://reviews.llvm.org/D37934<https://urldefense.proofpoint.com/v2/url?u=https-3A__reviews.llvm.org_D37934&d=DwMFaQ&c=DPL6_X_6JkXFx7AXWqB0tg&r=yfnu24japkhNGh-WqJObHXmH3mINtC_2FO828lrNpM0&m=s1muy0YuwDDElPQxgJ6vznc3dDBxkqEqdNbw6v9MesM&s=5prvINiyVrMl8bpYzRwFlVWxIlsjH79K0W9MyCGhDuM&e=>

This fixed this issue and also made it read both sets of registers via the XML target packets.

That should make things work, but it would be better if we modified the OpenOCD GDB server to respond with a thread ID when asked about its thread with the "qfThreadInfo" packet. Since it is a bare board connection, it should respond with "1" (one) to the "qfThreadInfo" packet followed by "l" to the next ThreadInfo packet (read GDB protocol docs on this.

Let me know if the patch mentioned above (which is already checked in) fixed your issues.

On Sep 17, 2017, at 3:50 AM, cui bixiong via lldb-dev <lldb-dev at lists.llvm.org<mailto:lldb-dev at lists.llvm.org>> wrote:

Hi：

    Currently I porting lldb for Hifive1 (riscv bare board) w/ openocd 0.10.0, but it always show "error: Process must be launched."

    I use GNU gdb to remote connect and debugging w/ the same openocd + elf, it work OK.

    I want to know how to launch Process in bare board?

    thanks a lot!

$ lldb
(lldb) log enable gdb-remote packets
(lldb) target create Build3/riscv-hello.elf
Current executable set to 'Build3/riscv-hello.elf' (riscv).
(lldb) gdb-remote 172.27.113.29:3333<https://urldefense.proofpoint.com/v2/url?u=http-3A__172.27.113.29-3A3333_&d=DwMFaQ&c=DPL6_X_6JkXFx7AXWqB0tg&r=yfnu24japkhNGh-WqJObHXmH3mINtC_2FO828lrNpM0&m=s1muy0YuwDDElPQxgJ6vznc3dDBxkqEqdNbw6v9MesM&s=VOu2PpXUGoyMKI8l3ZgwFP5o1vdRygwBr4rzl-CmFX0&e=>
<   1> send ack packet: +
history[1] tid=0x44c8 <   1> send packet: +
<   1> read packet: +
<  19> send SendPacketNoLock 2 packet: $QStartNoAckMode#b0
<   1> read packet: +
<   6> read packet: $OK#9a
<   1> send ack packet: +
<  41> send SendPacketNoLock 2 packet: $qSupported:xmlRegisters=i386,arm,mips#12
<  80> read packet: $PacketSize=3fff;qXfer:memory-map:read+;qXfer:features:read-;QStartNoAckMode+#08
<  26> send SendPacketNoLock 2 packet: $QThreadSuffixSupported#e4
<   4> read packet: $#00
<  27> send SendPacketNoLock 2 packet: $QListThreadsInStopReply#21
<   4> read packet: $#00
<  13> send SendPacketNoLock 2 packet: $qHostInfo#9b
<   4> read packet: $#00
<  10> send SendPacketNoLock 2 packet: $vCont?#49
<   4> read packet: $#00
<  27> send SendPacketNoLock 2 packet: $qVAttachOrWaitSupported#38
<   4> read packet: $#00
<  16> send SendPacketNoLock 2 packet: $qProcessInfo#dc
<   4> read packet: $#00
<   6> send SendPacketNoLock 2 packet: $qC#b4
<   7> read packet: $QC0#c4
<  16> send SendPacketNoLock 2 packet: $qfThreadInfo#bb
<   5> read packet: $l#6c
(lldb) thread list
error: Process must be launched.
(lldb) b main
Breakpoint 1: where = riscv-hello.elf`main at hello.c:3, address = 0x20400230
(lldb) thread continue
error: invalid thread
(lldb) process launch
<  38> send SendPacketNoLock 2 packet: $QSetSTDIN:2f6465762f7074732f343238#b6
<   4> read packet: $#00
<  39> send SendPacketNoLock 2 packet: $QSetSTDOUT:2f6465762f7074732f343238#17
<   4> read packet: $#00
<  39> send SendPacketNoLock 2 packet: $QSetSTDERR:2f6465762f7074732f343238#08
<   4> read packet: $#00
<  21> send SendPacketNoLock 2 packet: $QSetDisableASLR:1#ce
<   4> read packet: $#00
<  23> send SendPacketNoLock 2 packet: $QSetDetachOnError:1#f8
<   4> read packet: $#00
<  21> send SendPacketNoLock 2 packet: $QLaunchArch:riscv#8b
<   4> read packet: $#00
<  33> send SendPacketNoLock 2 packet: $QEnvironment:BINARY_TYPE_HPC=#fd
<   4> read packet: $#00
< 115> send SendPacketNoLock 2 packet: $A104,0,2f70726f6a2f6d746b31333836372f727369632d762f74657374696e672f4275696c64332f72697363762d68656c6c6f2e656c66#6c
<   4> read packet: $#00
error: process launch failed: 'A' packet returned an error: -1

Best Regards
--cuibixiong
_______________________________________________
lldb-dev mailing list
lldb-dev at lists.llvm.org<mailto:lldb-dev at lists.llvm.org>
http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev<https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.llvm.org_cgi-2Dbin_mailman_listinfo_lldb-2Ddev&d=DwMFaQ&c=DPL6_X_6JkXFx7AXWqB0tg&r=yfnu24japkhNGh-WqJObHXmH3mINtC_2FO828lrNpM0&m=s1muy0YuwDDElPQxgJ6vznc3dDBxkqEqdNbw6v9MesM&s=Yl9wZ2nbojjqtk8CUuyh6ANapwgmBwf8jEC0CFcmGNk&e=>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/lldb-dev/attachments/20170919/b9872a75/attachment-0001.html>