From 23e6ba8ef9f9967e0c15c6245fd92cdd5f60fc55 Mon Sep 17 00:00:00 2001 From: Wojtek Kosior Date: Fri, 11 Oct 2019 11:59:59 +0200 Subject: add initial bootloader work --- loader_stage2.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 loader_stage2.c (limited to 'loader_stage2.c') diff --git a/loader_stage2.c b/loader_stage2.c new file mode 100644 index 0000000..98ce571 --- /dev/null +++ b/loader_stage2.c @@ -0,0 +1,40 @@ +#include +#include +#include +#include + +void *const kernel_load_addr = ((void*) 0x8000); + +void __attribute__((section(".text.stage2main"))) +stage2(uint32_t r0, uint32_t r1, uint32_t atags) +{ + // Declare as unused + (void) r0; + (void) r1; + (void) atags; + + uart_puts("hello stage2!\n\r"); + + // get kernel size via uart (little endian) + uint32_t b0, b1, b2, b3; + + b0 = uart_getc(); + b1 = uart_getc(); + b2 = uart_getc(); + b3 = uart_getc(); + + uint32_t kernel_size = b0 | (b1 << 8) | (b2 << 16) | (b3 << 24); + + // load kernel at kernel_load_addr + char *dst = kernel_load_addr, *end = dst + kernel_size; + + while (dst < end) + *(dst++) = uart_getc(); + + // jump to kernel + // TODO also forward arguments (r0, r1, atags) + asm volatile("bx %0" :: "r" (kernel_load_addr) : "memory"); +} + +void *const _start = ((void*) stage2); // for linker script + -- cgit v1.2.3