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I am trying to cross-compile Linux for QEMU (RV64G ISA, lp64d ABI, Virt machine) using Buildroot. But apparently, GDB has been removed from buildroot version I'm using (2019.08), and is listed under the legacy list.

My objective is to be able to run RISC-V Linux application (in user-mode and softmmu) and with GDB debugging. I was able to build and run RISC-V apps using QEMU in both modes. But I didn't find a way to generate GDB like the other host utilities. Any ideas on how to do that?

noureddine-as
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  • Any reason not to just build upstream gdb directly? You want a host binary, not a target binary, so there's no particular need to involve buildroot, I think. – Peter Maydell Sep 26 '19 at 15:16

2 Answers2

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A possible procedure for building a riscv64-linux-gnu-gdb from scratch would be :

PREFIX=$(pwd)/gdb-8.3.1-riscv64-linux-gnu
wget ftp://ftp.gnu.org/gnu/gdb/gdb-8.3.1.tar.xz
tar Jxf gdb-8.3.1.tar.xz
mkdir gdb
cd gdb
../gdb-8.3.1/configure --program-prefix=riscv64-linux-gnu- -with-tui --target=riscv64-linux-gnu --prefix=${PREFIX}
make all install
cd -

Build artifacts will located in $(pwd)/gdb-8.3.1-riscv64-linux-gnu:

ls -gG gdb-8.3.1-riscv64-linux-gnu/bin/riscv64-linux-gnu-gdb
-rwxr-xr-x 1 80395824 Sep 26 14:16 gdb-8.3.1-riscv64-linux-gnu/bin/riscv64-linux-gnu-gdb

gdb-8.3.1-riscv64-linux-gnu/bin/riscv64-linux-gnu-gdb --version
GNU gdb (GDB) 8.3.1
Copyright (C) 2019 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.

If you don't want to build GDB with the TUI interface, remove --with-tui from the ./configure command.

I hope this helps.

Frant
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gdb has certainly not been removed from Buildroot! However, back when the RISC-V support was added in Buildroot, the gdb support was not included, and therefore BR2_PACKAGE_HOST_GDB_ARCH_SUPPORTS depends on !BR2_riscv, which hides gdb when the RISC-V architecture is selected.

So one would need to see if there is an upstream version of gdb that supports RISC-V, and if there is, remove the !BR2_riscv dependency, and add the appropriate dependencies to prevent the user from selecting older gdb versions that don't have RISC-V support.

Thomas Petazzoni
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