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Re: [Qemu-arm] [Qemu-devel] [PATCH v4 00/16] gdbstub: support for the mu


From: Philippe Mathieu-Daudé
Subject: Re: [Qemu-arm] [Qemu-devel] [PATCH v4 00/16] gdbstub: support for the multiprocess extension
Date: Thu, 8 Nov 2018 17:09:38 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1

On 6/11/18 12:05, Luc Michel wrote:
changes since v3:
   - patch 1    cpu_cluster.h: remove QEMU_ from the multiple includes
                guard #ifdef/#define [Alistair]

   - patch 1    cpu_cluster.c: include osdep.h first [Alistair]

   - patch 1    use uint64_t for cluster ID for prosperity :) [Philippe]

Actually my comment about 32-bit had the opposite meaning, I suppose having 256 kind of cpu cores in the same SoC is probably enough for a long time IMHO.


   - patch 1    auto-assign a cluster ID to newly created clusters [Philippe]

   - patch 2    fix mid-code variable declaration [Alistair]

   - patch 3    add a comment in gdb_get_cpu_pid() when retrieving CPU
                parent canonical path [Alistair]

   - patch 14   fix a typo in the commit message [Alistair]

changes since v2:
   - patch 1    introducing the cpu-cluster type. I didn't opt for an
                Interface, but I can add one if you think it's necessary.
                For now this class inherits from Device and has a
                cluster-id property, used by the GDB stub to compute a
                PID.

   - patch 2    removed GDB group related code as it has been replaced
                with CPU clusters

   - patch 2/8  moved GDBProcess target_xml field introduction into patch
                8 [Philippe]

   - patch 3    gdb_get_cpu_pid() now search for CPU being a child of a
                cpu-cluster object. Use the cluster-id to compute the PID.

   - patch 4    gdb_get_process() does not rely on s->processes array
                indices anymore as PIDs can now be sparse. Instead, iterate
                over the array to find the process.

   - patch 3/4  removed Reviewed-by tags because of substantial changes.

   - patch 4/7  read_thread_id() hardening [Philippe]

   - patch 12   safer vAttach packet parsing [Phillipe]

   - patch 16   put APUs and RPUs in different clusters instead of GDB
                groups

changes since v1:
   - rename qemu_get_thread_id() to gdb_fmt_thread_id() [Philippe]
   - check qemu_strtoul() return value for 'D' packets [Philippe]


This series adds support for the multiprocess extension of the GDB
remote protocol in the QEMU GDB stub.

This extension is useful to split QEMU emulated CPUs in different
processes from the point of view of the GDB client. It adds the
possibility to debug different kind of processors (e.g. an AArch64 and
an ARMv7 CPU) at the same time (it is not possible otherwise since GDB
expects an SMP view at the thread granularity.

CPUs are grouped using specially named QOM containers. CPUs that are
children of such a container are grouped under the same GDB process.

The last patch groups the CPUs of different model in the zynqmp machines
into separate processes.

To test this patchset, you can use the following commands:

(Note that this requires a recent enough GDB, I think GDB 7.2 is OK.
Also, it must be compiled to support both ARM and AArch64 architectures)

Run QEMU: (-smp 6 in xlnx-zcu102 enables both cortex-a53 and cortex-r5
CPUs)

qemu-system-aarch64 -M xlnx-zcu102 -gdb tcp::1234 -S -smp 6

Run the following commands in GDB:

target extended :1234
add-inferior
inferior 2
attach 2
info threads

I want to thanks the Xilinx's QEMU team who sponsored this work for
their collaboration and their prototype implementation.

Luc Michel (16):
   hw/cpu: introduce CPU clusters
   gdbstub: introduce GDB processes
   gdbstub: add multiprocess support to '?' packets
   gdbstub: add multiprocess support to 'H' and 'T' packets
   gdbstub: add multiprocess support to vCont packets
   gdbstub: add multiprocess support to 'sC' packets
   gdbstub: add multiprocess support to (f|s)ThreadInfo and
     ThreadExtraInfo
   gdbstub: add multiprocess support to Xfer:features:read:
   gdbstub: add multiprocess support to gdb_vm_state_change()
   gdbstub: add multiprocess support to 'D' packets
   gdbstub: add support for extended mode packet
   gdbstub: add support for vAttach packets
   gdbstub: processes initialization on new peer connection
   gdbstub: gdb_set_stop_cpu: ignore request when process is not attached
   gdbstub: add multiprocess extension support
   arm/xlnx-zynqmp: put APUs and RPUs in separate CPU clusters

  include/hw/arm/xlnx-zynqmp.h |   3 +
  include/hw/cpu/cluster.h     |  38 +++
  gdbstub.c                    | 632 ++++++++++++++++++++++++++++++-----
  hw/arm/xlnx-zynqmp.c         |  21 +-
  hw/cpu/cluster.c             |  59 ++++
  hw/cpu/Makefile.objs         |   2 +-
  6 files changed, 674 insertions(+), 81 deletions(-)
  create mode 100644 include/hw/cpu/cluster.h
  create mode 100644 hw/cpu/cluster.c




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