Merge remote-tracking branch 'remotes/stsquad/tags/pull-testing-and-misc-110720-2' into staging

Testing and misc build updates:

  - tests/vm support for aarch64 VMs
  - tests/tcg better cross-compiler detection
  - update docker tooling to support registries
  - update docker support for xtensa
  - gitlab build docker images and store in registry
  - gitlab use docker images for builds
  - a number of skipIf updates to support move
  - linux-user MAP_FIXED_NOREPLACE fix
  - qht-bench compiler tweaks
  - configure fix for secret keyring
  - tsan fiber annotation clean-up
  - doc updates for mttcg/icount/gdbstub
  - fix cirrus to use brew bash for iotests
  - revert virtio-gpu breakage
  - fix LC_ALL to avoid sorting changes in iotests

# gpg: Signature made Sat 11 Jul 2020 15:56:42 BST
# gpg:                using RSA key 6685AE99E75167BCAFC8DF35FBD0DB095A9E2A44
# gpg: Good signature from "Alex Bennée (Master Work Key) <alex.bennee@linaro.org>" [full]
# Primary key fingerprint: 6685 AE99 E751 67BC AFC8  DF35 FBD0 DB09 5A9E 2A44

* remotes/stsquad/tags/pull-testing-and-misc-110720-2: (50 commits)
  iotests: Set LC_ALL=C for sort
  Revert "vga: build virtio-gpu as module"
  tests: fix "make check-qtest" for modular builds
  .cirrus.yml: add bash to the brew packages
  tests/docker: update toolchain set in debian-xtensa-cross
  tests/docker: fall back more gracefully when pull fails
  docs: Add to gdbstub documentation the PhyMemMode
  docs/devel: add some notes on tcg-icount for developers
  docs/devel: convert and update MTTCG design document
  tests/qht-bench: Adjust threshold computation
  tests/qht-bench: Adjust testing rate by -1
  travis.yml: Test also the other targets on s390x
  shippable: pull images from registry instead of building
  testing: add check-build target
  containers.yml: build with docker.py tooling
  gitlab: limit re-builds of the containers
  tests: improve performance of device-introspect-test
  gitlab: add avocado asset caching
  gitlab: enable check-tcg for linux-user tests
  linux-user/elfload: use MAP_FIXED_NOREPLACE in pgb_reserved_va
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

docs/system/gdb.rst

@@ -87,3 +87,23 @@ three commands you can query and set the single step behavior:
       (gdb) maintenance packet Qqemu.sstep=0x5
       sending: "qemu.sstep=0x5"
       received: "OK"
+
+
+Another feature that QEMU gdbstub provides is to toggle the memory GDB
+works with, by default GDB will show the current process memory respecting
+the virtual address translation.
+
+If you want to examine/change the physical memory you can set the gdbstub
+to work with the physical memory rather with the virtual one.
+
+The memory mode can be checked by sending the following command:
+
+``maintenance packet qqemu.PhyMemMode``
+    This will return either 0 or 1, 1 indicates you are currently in the
+    physical memory mode.
+
+``maintenance packet Qqemu.PhyMemMode:1``
+    This will change the memory mode to physical memory.
+
+``maintenance packet Qqemu.PhyMemMode:0``
+    This will change it back to normal memory mode.