cmake: boards: make QEMU icount sleep parameter configurable

When QEMU is running in icount mode, the behaviour regarding
the CPU being in sleep mode is configurable, with the default
value being set to 'off'. In this case, instruction counting
continues even when the CPU is sleeping or no target time is
set in the system timer. If the sleep parameter is set to
'on', instruction counting stops if the CPU is sleeping, and
the instruction count will fast-forward directly to the next
target time once it is being set.

In the Xilinx derivative of QEMU (which simulates ZynqMP and
Zynq-7000 SoCs), the default configuration causes QEMU to no
longer accept control commands via the console or remotely
whenever Zephyr enters and remains in idle mode.

Therefore, this commit makes the value of the sleep para-
meter of the icount functionality configurable, with the
default value remaining 'off'. The value can be changed at
board level alongside with the specification of the icount
shift value.

Signed-off-by: Immo Birnbaum <[email protected]>

Author: ibirnbaum

boards/Kconfig

@@ -54,6 +54,17 @@ config QEMU_ICOUNT_SHIFT
 	  The virtual CPU will execute one instruction every 2^N nanoseconds
 	  of virtual time, where N is the value provided here.
 
+config QEMU_ICOUNT_SLEEP
+	bool "QEMU icount sleep mode enable"
+	depends on QEMU_ICOUNT
+	help
+	  When the virtual CPU is sleeping, the virtual time will advance
+	  at default speed unless this option is set. With this option set,
+	  the virtual time will jump to the next timer deadline instantly
+	  whenever the virtual CPU goes to sleep mode and will not advance
+	  if no timer is enabled. This behavior gives deterministic execution
+	  times from the guest point of view.
+
 config QEMU_IVSHMEM_PLAIN_MEM_SIZE
 	int "QEMU ivshmem-plain shared memory size in mega-bytes"
 	default 1

boards/arm/qemu_cortex_a9/Kconfig.defconfig

@@ -71,7 +71,9 @@ endif # NETWORKING
 if QEMU_ICOUNT
 
 	config QEMU_ICOUNT_SHIFT
-	default 3
+	default 8
+	config QEMU_ICOUNT_SLEEP
+	default y
 
 endif # QEMU_ICOUNT
 

cmake/emu/qemu.cmake

@@ -74,9 +74,15 @@ endif()
 list(APPEND QEMU_FLAGS -mon chardev=con,mode=readline)
 
 if(CONFIG_QEMU_ICOUNT)
-  list(APPEND QEMU_FLAGS
+  if(CONFIG_QEMU_ICOUNT_SLEEP)
+    list(APPEND QEMU_FLAGS
+	  -icount shift=${CONFIG_QEMU_ICOUNT_SHIFT},align=off,sleep=on
+	  -rtc clock=vm)
+  else()
+    list(APPEND QEMU_FLAGS
 	  -icount shift=${CONFIG_QEMU_ICOUNT_SHIFT},align=off,sleep=off
 	  -rtc clock=vm)
+  endif()
 endif()
 
 # Add a BT serial device when building for bluetooth, unless the