[PATCH v2 2/2] hw/arm/armv7m: Downgrade CPU reset handler priority

[Stephanos Ioannidis <root@stephanos.io>]

The ARMv7-M CPU reset handler, which loads the initial SP and PC
register values from the vector table, is currently executed before
the ROM reset handler (rom_reset), and this causes the devices that
alias low memory region (e.g. STM32F405 that aliases the flash memory
located at 0x8000000 to 0x0) to load an invalid reset vector of 0 when
the kernel image is linked to be loaded at the high memory address.

For instance, it is norm for the STM32F405 firmware ELF image to have
the text and rodata sections linked at 0x8000000, as this facilitates
proper image loading by the firmware burning utility, and the processor
can execute in place from the high flash memory address region as well.

In order to resolve this issue, this commit downgrades the ARMCPU reset
handler invocation priority level to -1 such that it is always executed
after the ROM reset handler, which has a priority level of 0.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
---
 hw/arm/armv7m.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/arm/armv7m.c b/hw/arm/armv7m.c
index 7531b97ccd..8b7c4b12a6 100644
--- a/hw/arm/armv7m.c
+++ b/hw/arm/armv7m.c
@@ -352,7 +352,8 @@ void armv7m_load_kernel(ARMCPU *cpu, const char *kernel_filename, int mem_size)
      * way A-profile does it. Note that this means that every M profile
      * board must call this function!
      */
-    qemu_register_reset(armv7m_reset, cpu);
+    qemu_register_reset_with_priority(
+        QEMU_RESET_PRIORITY_LEVEL(-1), armv7m_reset, cpu);
 }
 
 static Property bitband_properties[] = {
-- 
2.17.1