hw/arm/boot: Clarify why arm_setup_firmware_boot() doesn't set env->b…

…oot_info

The code path for booting firmware doesn't set env->boot_info. At
first sight this looks odd, so add a comment saying why we don't.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-id: 20190131112240.8395-5-peter.maydell@linaro.org

hw/arm/boot.c

@@ -1182,7 +1182,8 @@ static void arm_setup_firmware_boot(ARMCPU *cpu, struct arm_boot_info *info)
 
     /*
      * We will start from address 0 (typically a boot ROM image) in the
-     * same way as hardware.
+     * same way as hardware. Leave env->boot_info NULL, so that
+     * do_cpu_reset() knows it does not need to alter the PC on reset.
      */
 }