Hi Michal,
It appears there's a problem with the default memory map in u-boot's "microblaze-generic" configuration. We have (from include/configs/microblaze-generic.h):
/* ddr sdram - main memory */ #define CONFIG_SYS_SDRAM_BASE XILINX_RAM_START #define CONFIG_SYS_SDRAM_SIZE XILINX_RAM_SIZE #define CONFIG_SYS_MEMTEST_START CONFIG_SYS_SDRAM_BASE #define CONFIG_SYS_MEMTEST_END (CONFIG_SYS_SDRAM_BASE + 0x1000)
/* global pointer */ #define CONFIG_SYS_GBL_DATA_SIZE 128 /* size of global data */ /* start of global data */ #define CONFIG_SYS_GBL_DATA_OFFSET (CONFIG_SYS_SDRAM_BASE + CONFIG_SYS_SDRAM_SIZE - CONFIG_SYS_GBL_DATA_SIZE)
/* monitor code */ #define SIZE 0x40000 #define CONFIG_SYS_MONITOR_LEN (SIZE - CONFIG_SYS_GBL_DATA_SIZE) #define CONFIG_SYS_MONITOR_BASE (CONFIG_SYS_GBL_DATA_OFFSET - CONFIG_SYS_MONITOR_LEN) #define CONFIG_SYS_MONITOR_END (CONFIG_SYS_MONITOR_BASE + CONFIG_SYS_MONITOR_LEN) #define CONFIG_SYS_MALLOC_LEN SIZE #define CONFIG_SYS_MALLOC_BASE (CONFIG_SYS_MONITOR_BASE - CONFIG_SYS_MALLOC_LEN)
/* stack */ #define CONFIG_SYS_INIT_SP_OFFSET CONFIG_SYS_MONITOR_BASE
This builds a memory map like the following:
0x47f80000 - 0x47fbffff: malloc region 0x47fc0000 - 0x47ffff7f: monitor 0x47ffff80 - 0x47ffffff: globals
The initial SP is set to 0x47fc0000. This collides with the malloc region, and when the malloc region is cleared during mem_malloc_init(), the stack is wiped out. This includes the return address from mem_malloc_init(), among other things.
Can you confirm that CONFIG_SYS_INIT_SP_OFFSET should be CONFIG_SYS_MALLOC_BASE instead of CONFIG_SYS_MONITOR_BASE? That agrees with your memory diagram at include/configs/microblaze-generic.h:103.
thanks, Graeme