gdb debugging

[yli147]

I'm trying to use gdb to debug with the bazel-bin/salus, some steps are as below, but it looks like the gdb can't find the the source code for example main.rs based on symbol file bazel-bin/salus. Has anyone one worked with gdb ? Thanks

$ gdb-multiarch bazel-bin/salus
$ set architecture riscv:rv64
$ target remote localhost:1234
$ set directories ./src/
$ add-symbol-file ./bazel-bin/test-workloads/guestvm
$ add-symbol-file ./bazel-bin/test-workloads/tellus

[rajnesh-kanwal]

Here are the steps which seem to work fine for me. Looks like gdb-multiarch isn't reading debug info from provided executable for some reason, strange. With your instructions I have to do add-symbol-file ./bazel-bin/salus to get it working. set directories ./src/ is not needed. Also we don't support guest debugging as of right now.

$ gdb-multiarch --symbols=bazel-bin/salus
$ set architecture riscv:rv64
$ target remote localhost:1234
$ b primary_init
$ c

After the breakpoint if I go to the TUI mode (Ctrl-x + a) I can see main.rs.

[yli147]

Hi Rajnesh, Thanks for your response, still not working even by using "gdb-multiarch --symbols=bazel-bin/salus", what's the version of your rust toolchain and gdb ? did you add some speicfic rust build option ? or anything other ?

[yli147]

And Yes, guest application debugging is not available right after the sret instruction

[rajnesh-kanwal]

gdb-multiarch -v
GNU gdb (Ubuntu 9.2-0ubuntu1~20.04.1) 9.2

Strange. These steps seem to work fine for me.

[yli147]

I'm using the below commands to build salus and debug, is there anything wrong ? By the way I can debug one riscv hello world application written by rust. so now I guess it should not the gdb issue. Are there any build options to force to build a debug version of salus ? or somthing related to rust toolchain ? Thanks

$ git clone https://github.com/rivosinc/salus.git
$ cd salus/
$ git submodule update --init
$ wget -c https://github.com/bazelbuild/bazelisk/releases/download/v1.16.0/bazelisk-linux-amd64
chmod a+x bazelisk-linux-amd64
$ ./bazelisk-linux-amd64 build //:salus-all
$ {QEMU}/build/riscv64-softmmu/qemu-system-riscv64
-M virt,aia=aplic-imsic,aia-guests=4 -cpu rv64,v=on,vlen=256,elen=64,x-smaia=true,x-ssaia=true,sscofpmf=true -smp 1 -m 2048 -nographic
-kernel bazel-bin/salus
-device guest-loader,kernel=bazel-bin/test-workloads/tellus_guestvm,addr=0xc0200000 -s -S

[yli147]

Oh, it is caused by the --compilation_mode, with the below change, I can debug the salus now ! Thanks

$ vim ./.bazelrc
Change the line
build --compilation_mode=opt
=>
build --compilation_mode=dbg

[yli147]

By the way, I can also debug the guest application by using the following steps:

$ gdb-multiarch --symbols=bazel-bin/salus
$ set architecture riscv:rv64
$ target remote localhost:1234
$ b _run_guest
$ b _guest_exit
$ c
It will stop in _run_guest, then step to the sret instruction
$ b *0x80200000
$ c
it will stop at 0x80200000 which is of the guest application
$ remove-symbol-file -a 0x80200000
$ add-symbol-file ./bazel-bin/test-workloads/tellus
$ b tellus.rs:464
$ c

[rajnesh-kanwal]

Oh, it is caused by the --compilation_mode, with the below change, I can debug the salus now ! Thanks

$ vim ./.bazelrc Change the line build --compilation_mode=opt => build --compilation_mode=dbg

You can avoid all this by using make run_tellus_gdb, it takes care of everything, including invoking qemu with -s -S options.

[yli147]

ok, thanks !