Bootstrap for stm32f103

bootstrap.s

@ stm32f103 has 0x5000 (20K) SRAM                                                                                       
@ SRAM is starting from 0x20000000                                                                                         
@ so stack is eq 0x20000000 + 0x5000 = 0x20005000                                                                          
@ flash starts from 0x08000000                                                                                             
                                                                                                                           
.syntax unified                                                                                                            
.thumb                                                                                                                     
.cpu cortex-m3                                                                                                             
                                                                                                                           
.equ Stack_up, 0x20005000                                                                                                  
                                                                                                                           
.word  Stack_up     @ stack header                                                                                         
.word  Reset + 1    @ start of program. +1 for format in Thumb instead ARM. 
                    @ Stm32 understands only set of Thumb commands
                                                                                                                           
Reset:  B Reset

stm32f103.ld

MEMORY
{
  rom : org = 0x08000000, l = 64K
  ram : org = 0x20000000, l = 20K
}

SECTIONS
{
  .text : {
    *(.text);
  } > rom

  .data : {
    *(.data);
  } > ram AT>rom = 0xff
}