[Qemu-devel] armv7m/stm32f205 not starting if code linked from 0x08000000

[Liviu Ionescu]

Hi Alistair/Peter,

I am having difficulties to make the armv7m code run if linked from 0x08000000.

based on the tracing info that I have (copied below), it seems that the cpu 
throws an early exception, properly caught by the cpu and displayed (see the 
indented lines).

this is weird, since displaying these lines inside the UsageFault_Handler means 
the alias works and the core can execute code from 0x08000000.

my guess is that there is a bug in the reset code preventing the cpu to fetch 
the Reset_Handler address from the first words in memory.

I traced the cpu.c: arm_cpu_reset(CPUState *s) function and around line 170 
there are two calls to initialise msp and pc:

            initial_msp = ldl_phys(s->as, 0);
            initial_pc = ldl_phys(s->as, 4);

in my environment both return 0, probably not being able to fetch data from the 
aliased region.

could someone suggest a fix for this problem?


regards,

Liviu





GNU ARM Eclipse 64-bits QEMU v2.3.50 (qemu-system-gnuarmeclipse).
QEMU 2.3.50 monitor - type 'help' for more information

(qemu) memory_region_init("system", 18446744073709551615)
memory_region_init("io", 65536)
memory_region_init("stm32f2xx-syscfg", 1024)
memory_region_init("stm32f2xx-usart", 8192)
memory_region_init("stm32f2xx-usart", 8192)
memory_region_init("stm32f2xx-usart", 8192)
memory_region_init("stm32f2xx-usart", 8192)
memory_region_init("stm32f2xx-usart", 8192)
memory_region_init("stm32f2xx-usart", 8192)
memory_region_init("stm32f2xx_timer", 16384)
memory_region_init("stm32f2xx_timer", 16384)
memory_region_init("stm32f2xx_timer", 16384)
memory_region_init("stm32f2xx_timer", 16384)
memory_region_init("STM32F205.flash", 1048576)
memory_region_init("STM32F205.flash.alias", 1048576)
memory_region_init("STM32F205.sram", 131072)
memory_region_init("bitband", 33554432)
memory_region_init("bitband", 33554432)
armv7m_nvic_instance_init()
armv7m_nvic_realize()
NVIC: 96 irqs
Load   8024 bytes at 0x08000000-0x08001F57.
Load    116 bytes at 0x08001F58-0x08001FCB.
Load    704 bytes at 0x20000074-0x20000333.
memory_region_init("gic_dist", 4096)
memory_region_init("nvic", 4096)
memory_region_init("nvic_sysregs", 4096)
memory_region_init("nvic-gic", 3072)
memory_region_init("armv7m.hack", 4096)
armv7m_nvic_reset()
mr rd32(0xE000ED34) 0x00000000)
mr rd32(0xE000ED38) 0x00000000)
mr rd32(0xE000ED28) 0x00000000)
        [UsageFault]
        Stack frame:
         R0 =  00000000
         R1 =  00000000
         R2 =  00000000
         R3 =  00000000
         R12 = 00000000
         LR =  00000000
         PC =  00000000
         PSR = 40000000
        FSR/FAR:
         CFSR =  00000000
mr rd32(0xE000ED2C) 0x00000000)
         HFSR =  00000000
mr rd32(0xE000ED30) 0x00000000)
         DFSR =  00000000
mr rd32(0xE000ED3C) 0x00000000)
         AFSR =  00000000
        Misc
         LR/EXC_RETURN= FFFFFFF9