arm-bsp/docs: Minor fvp-baser-aemv8r64 updates

* Add clarification on how to mount p9 device
 * Remove instruction to use ctrl + c to stop FVP
 * Add cache_state_modelled to Known Issues

Issue-Id: SCM-3871
Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>
Change-Id: I122c5ae5b3ceee1d106205d93a006f75bdbfa2bf
Signed-off-by: Jon Mason <jon.mason@arm.com>

meta-arm-bsp/documentation/fvp-baser-aemv8r64.md

@@ -171,18 +171,11 @@ To run an image after the build is done with the Real-Time Linux kernel
 
 **Note:** The terminal console login is `root` without password.
 
-To finish the fvp emulation, you need to close the telnet session and stop the
-runfvp script:
-
-1. To close the telnet session:
+To finish the fvp emulation, you need to close the telnet session:
 
  - Escape to telnet console with ``ctrl+]``.
  - Run ``quit`` to close the session.
 
-2. To stop the runfvp:
-
- - Type ``ctrl+c`` and wait for kas process to finish.
-
 ### File sharing between host and fvp
 It is possible to share a directory between the host machine and the fvp using
 the virtio P9 device component included in the kernel. To do so, create a
@@ -195,6 +188,14 @@ launching the model:
 
     --parameter 'bp.virtiop9device.root_path=/path/to/host-mount-dir'
 
+e.g. for the standard Linux kernel:
+
+    kas shell --keep-config-unchanged \
+       meta-arm/kas/fvp-baser-aemv8r64-bsp.yml \
+           --command "../layers/meta-arm/scripts/runfvp \
+           --console --parameter
+           'bp.virtiop9device.root_path=/path/to/host-mount-dir'"
+
 Once you are logged into the fvp, the host directory can be mounted in a
 directory on the model using the following command:
 
@@ -216,6 +217,8 @@ Known Issues and Limitations
 - Only PSCI CPU\_ON and CPU\_OFF functions are supported
 - Linux kernel does not support booting from secure EL2 on Armv8-R AArch64
 - Linux KVM does not support Armv8-R AArch64
+- Enabling the FVP parameter `cache_state_modelled` is incompatible with virtio
+  devices
 
 Change Log
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