Merge branch 'bob' of https://repo.or.cz/RPi-MMU-example into alice

4 files changed, 47 insertions, 5 deletions

diff --git a/Makefile b/Makefile
index b05600f..96a809a 100644
--- a/Makefile
+++ b/Makefile
@@ -44,11 +44,13 @@ loader.img : loader.elf
 qemu-elf : kernel.elf
 	qemu-system-arm -m 256 -M raspi2 -serial stdio -kernel $^
 
-qemu-bin : loader.img kernel7.img pipe_image
+qemu-bin : loader.elf kernel7.img pipe_image
 	./pipe_image | qemu-system-arm -m 256 -M raspi2 -serial stdio -kernel $<
 
-qemu-loader : loader.img
-	qemu-system-arm -m 256 -M raspi2 -serial stdio -kernel $^
+run-on-rpi : kernel7.img pipe_image
+	./pipe_image | socat FILE:/dev/ttyUSB0,b115200,raw -
+	sleep 1
+	screen  /dev/ttyUSB0 115200,cs8,-parenb,-cstopb,-hupcl
 
 pipe_image : pipe_image.c RS-232/rs232.c
 	gcc -Wall -std=gnu99 -O3 $^ -o $@
diff --git a/kernel.c b/kernel.c
index f5a2b2e..c5918a1 100644
--- a/kernel.c
+++ b/kernel.c
@@ -8,6 +8,12 @@ void kernel_main(uint32_t r0, uint32_t r1, uint32_t atags)
   (void) atags;
 
   uart_init();
+
+  // When we attach screen session after loading kernel with socat
+  // we miss kernel's greeting... So we'll make the kernel wait for
+  // one char we're going to send from within screen
+  uart_getc();
+  
   uart_puts("Hello, kernel World!\r\n");
 
   uint32_t ID_MMFR0;
@@ -16,7 +22,7 @@ void kernel_main(uint32_t r0, uint32_t r1, uint32_t atags)
 
   char *paging;
 
-  switch(ID_MMFR0 & 7) /* lowest 4 bits indicate VMSA support */ {
+  switch(ID_MMFR0 & 0xf) /* lowest 4 bits indicate VMSA support */ {
   case 0 : paging = "no paging\n\r"; break;
   case 1 : paging = "implementation defined paging\n\r"; break;
   case 2 : paging = "VMSAv6, with cache and TLB type registers\n\r"; break;
@@ -27,6 +33,28 @@ void kernel_main(uint32_t r0, uint32_t r1, uint32_t atags)
   }
 
   uart_puts(paging);
+
+  uint32_t CPSR;
+  // get content of current program status register to check the current
+  // processor mode
+  asm("mrs %0, cpsr" : "=r" (CPSR) :: "memory");
+
+  char *mode;
+  
+  switch(CPSR & 0x1f) /* lowest 5 bits indicate processor mode */ {
+  case 0x10 : mode = "User (PL0)"; break;
+  case 0x11 : mode = "FIQ (PL1)"; break;
+  case 0x12 : mode = "IRQ (PL1)"; break;
+  case 0x13 : mode = "Supervisor (PL1)"; break;
+  case 0x16 : mode = "Monitor (PL1)"; break;
+  case 0x17 : mode = "Abort (PL1)"; break;
+  case 0x1a : mode = "Hyp (PL2)"; break;
+  case 0x1b : mode = "Undefined (PL1)"; break;
+  case 0x1f : mode = "System (PL1)"; break;
+  default : mode = "Unknown mode"; break;
+  }
+
+  uart_puts(mode);
   
   while (1)
     uart_putc(uart_getc());
diff --git a/linker.ld b/linker.ld
index c9a91df..e7bfdb8 100644
--- a/linker.ld
+++ b/linker.ld
@@ -9,8 +9,11 @@ SECTIONS
     /* Since we're using a bootloader now, we can compile the kernel */
     /* for 0x8000 and bootloader will load it properly (although it */
     /* itself still has to be compiled for 0x10000) */
+    /* rpi-open-firmware, ont he other hand, loads kernel at 0x2000000 */
+    /* This issue is also to be avoided by the use of bootloader */
     . = 0x8000;
     /* For AArch64, use . = 0x80000; Unless this too is wrong in qemu… */
+    
     __start = .;
     __text_start = .;
     .text :
diff --git a/loader_stage1.ld b/loader_stage1.ld
index ce11095..507e367 100644
--- a/loader_stage1.ld
+++ b/loader_stage1.ld
@@ -6,8 +6,17 @@ SECTIONS
     /* Warning! Internet says RPis in 32-bit mode load binary at 0x8000! */
     /* My experiments do, however, show, that qemu emulating RPi2 */
     /* loads it at 0x10000! (took some pain to find out) */
-    . = 0x10000;
+    
+    /* . = 0x10000; */
+    
+    /* rpi-open-firmware, on the other hand, loads it at 0x2000000 */
+    /* (and this should be not-so-hard to change by modifying the */
+    /* firmware */
+    
+    . = 0x2000000;
+
     /* For AArch64, use . = 0x80000; Unless this too is wrong */
+    
     __start = .;
     __text_start = .;
     .text :