From 23e6ba8ef9f9967e0c15c6245fd92cdd5f60fc55 Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <kwojtus@protonmail.com>
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 <stddef.h>
+#include <stdint.h>
+#include <uart.h>
+#include <global.h>
+
+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


From bc9ee9f0acc0ec26acda4ffd8f5fdcd04a6375c5 Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <kwojtus@protonmail.com>
Date: Fri, 11 Oct 2019 18:59:16 +0200
Subject: initialize uart in bootloader's stage2, not stage1

---
 Makefile        | 2 +-
 loader_stage1.c | 5 -----
 loader_stage2.c | 2 +-
 3 files changed, 2 insertions(+), 7 deletions(-)

(limited to 'loader_stage2.c')

diff --git a/Makefile b/Makefile
index 2fbb0aa..7632283 100644
--- a/Makefile
+++ b/Makefile
@@ -32,7 +32,7 @@ loader_stage2_embeddable.o : loader_stage2.img
 loader_stage1.o : loader_stage1.c
 	arm-none-eabi-gcc $(CFLAGS) -c $^ -o $@
 
-loader.elf : boot.o loader_stage1.o uart.o loader_stage2_embeddable.o
+loader.elf : boot.o loader_stage1.o loader_stage2_embeddable.o
 	arm-none-eabi-gcc -T loader_stage1.ld -o $@ -ffreestanding -O2 -nostdlib $^ -lgcc
 
 loader.img : loader.elf
diff --git a/loader_stage1.c b/loader_stage1.c
index 9492747..d209c15 100644
--- a/loader_stage1.c
+++ b/loader_stage1.c
@@ -1,6 +1,5 @@
 #include <stddef.h>
 #include <stdint.h>
-#include <uart.h>
 #include <global.h>
 
 char *const stage2_addr = ((void*) 0x4000);
@@ -15,10 +14,6 @@ extern char
 
 void kernel_main(uint32_t r0, uint32_t r1, uint32_t atags)
 {
-  // uart_init() call to be moved to stage2...
-  uart_init();
-  uart_puts("Hello, bootloader World!\r\n");
-
   // stage2 of the bootloader is a blob embedded in executable;
   // copy it over to it's destination place
   // TODO implement a memcpy() somewhere and use it instead of loops
diff --git a/loader_stage2.c b/loader_stage2.c
index 98ce571..e221dda 100644
--- a/loader_stage2.c
+++ b/loader_stage2.c
@@ -13,7 +13,7 @@ stage2(uint32_t r0, uint32_t r1, uint32_t atags)
   (void) r1;
   (void) atags;
 
-  uart_puts("hello stage2!\n\r");
+  uart_init();
 
   // get kernel size via uart (little endian)
   uint32_t b0, b1, b2, b3;
-- 
cgit v1.2.3