Remote 'g' packet reply is too long

gdb linux-kernel kvm
contemplatingzombie picture contemplatingzombie · Dec 29, 2011 · Viewed 19.3k times · Source

I am trying to debug Linux kernel with kvm vm. I am getting an error message "Remote 'g' packet reply is too long". My host is 64-bit and so is my vm.

My steps:

  1. Start the VM with custom -kernel, -initrd and -append options.
  2. Start gdb
  3. Execute "set architecture i386:x86-64:intel"
  4. Execute "add-symbol-file linux-3.0/vmlinux"
  5. Execute "show arch" to verify its still "i386:x86-64:intel"
  6. Execute "target remote localhost:1234"
  7. Execute "continue"
  8. Press Ctrl+C, I get the above message.

Has anyone faced this problem?

Answer

Gabriel picture Gabriel · May 9, 2013

gdb doesn't work well against a cpu that switches between instruction sets at runtime. Wait for the kernel to leave early boot before connecting, and don't use qemu's -S flag.

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