Currently the bootwrapper only works for Fast Models, as the
Versatile Express BootMonitor doesn't allow execution of elf files
with multiple program headers. A workaround is to load the kernel
image separately from the bootwrapper elf file, using BootMonitor.
Note that BootMonitor will crash, when trying to load a uImage
kernel, zImage is needed instead. The same applies for the actual
elf file, it should be flashed, instead of loaded from the MMC.
- A new make target has been added (board), which uses a different
linker script (board.lds.S), without including the kernel image.
- A major difference between the real target and Fast Models, is
that BootMonitor has already placed CPU1 in wfi state.
- In order to run the bootwrapper on CPU1 we have to generate a
software interrupt first and point it to jump to the right
location, by writing the address to SYS_FLAGS.
- Monitor location has been updated to the last 8MBs of the 2GB
memory address space. Previously it was on the last 256MBs.
- Code relocation for CPU1 wfe state, has been moved behind the
monitor section, instead of the initrd region.
Usage example in BootMonitor (with board.axf being already flashed):
- load zImage LOAD_ADDRESS 0x80008000
- flash run board
Signed-off-by: Alexander Spyridakis <a.spyridakis at virtualopensystems.com>
---
Makefile | 23 +++++++++++++++++++----
board.lds.S | 24 ++++++++++++++++++++++++
boot.S | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++----
model.lds.S | 5 +++--
4 files changed, 99 insertions(+), 10 deletions(-)
create mode 100644 board.lds.S
diff --git a/Makefile b/Makefile
index 995fd8f..92f013f 100644
--- a/Makefile
+++ b/Makefile
@@ -22,7 +22,9 @@ KERNEL = uImage
IMAGE = linux-system.axf
SEMIIMG = linux-system-semi.axf
+BOARD = board.axf
LD_SCRIPT = model.lds.S
+B_LD_SCRIPT = board.lds.S
CC = $(CROSS_COMPILE)gcc
@@ -32,14 +34,18 @@ LD = $(CROSS_COMPILE)ld
export CROSS_COMPILE ARCH
# Build all wrappers
-all: $(IMAGE) $(SEMIIMG)
+all: $(IMAGE) $(SEMIIMG) $(BOARD)
# Build just the semihosting wrapper
semi: $(SEMIIMG)
+# Build wrapper for the versatile express board
+board: $(BOARD)
+
clean distclean:
- rm -f $(IMAGE) $(SEMIIMG) \
- model.lds modelsemi.lds $(OBJS) $(KERNEL)
+ rm -f $(IMAGE) $(SEMIIMG) $(BOARD) \
+ model.lds modelsemi.lds board.lds \
+ board.o $(OBJS) $(KERNEL)
$(KERNEL): $(KERNEL_SRC)/arch/arm/boot/uImage
cp $< $@
@@ -50,12 +56,18 @@ $(IMAGE): $(OBJS) model.lds $(KERNEL) $(FILESYSTEM) Makefile
$(SEMIIMG): $(OBJS) modelsemi.lds
$(LD) -o $@ $(OBJS) --script=modelsemi.lds
+$(BOARD): board.o monitor.o board.lds Makefile
+ $(LD) -o board.axf --script=board.lds
+
boot.o: $(BOOTLOADER)
$(CC) $(CPPFLAGS) -DKCMD='$(KCMD)' -c -o $@ $<
monitor.o: $(MONITOR)
$(CC) $(CPPFLAGS) -c -o $@ $<
+board.o: $(BOOTLOADER)
+ $(CC) $(CPPFLAGS) -DKCMD='$(KCMD)' -DBOARD -c -o $@ $<
+
%.o: %.c
$(CC) $(CPPFLAGS) -O2 -ffreestanding -Ilibfdt -c -o $@ $<
@@ -65,6 +77,9 @@ model.lds: $(LD_SCRIPT) Makefile
modelsemi.lds: $(LD_SCRIPT) Makefile
$(CC) $(CPPFLAGS) -DSEMIHOSTING=1 -E -P -C -o $@ $<
+board.lds: $(B_LD_SCRIPT) Makefile
+ $(CC) $(CPPFLAGS) -DBOARD -E -P -C -o $@ $<
+
$(KERNEL_SRC)/arch/arm/boot/uImage: force
$(MAKE) -C $(KERNEL_SRC) -j4 uImage
@@ -79,4 +94,4 @@ force: ;
Makefile: ;
-.PHONY: all semi clean distclean config.mk config-default.mk
+.PHONY: all semi board clean distclean config.mk config-default.mk
\ No newline at end of file
diff --git a/board.lds.S b/board.lds.S
new file mode 100644
index 0000000..62bcede
--- /dev/null
+++ b/board.lds.S
@@ -0,0 +1,24 @@
+OUTPUT_FORMAT("elf32-littlearm")
+OUTPUT_ARCH(arm)
+TARGET(binary)
+
+INPUT(./board.o)
+INPUT(./monitor.o)
+
+PHYS_OFFSET = 0x80000000;
+MON_OFFSET = 0xff800000;
+
+SECTIONS
+{
+ . = PHYS_OFFSET + 0x8000;
+ kernel = .;
+
+ . = PHYS_OFFSET + 0x10000000;
+ fs_start = .;
+
+ . = MON_OFFSET;
+ monitor = .;
+
+ .monitor : { monitor.o }
+ .text : { board.o }
+}
diff --git a/boot.S b/boot.S
index 61cd93f..f65446d 100644
--- a/boot.S
+++ b/boot.S
@@ -12,10 +12,24 @@
.arch_extension virt
.text
+ .equ GICD_CTLR, 0x2c001000
+ .equ VE_SYS_FLAGS, 0x1c010030
.globl start
start:
#ifdef SMP
+#ifdef BOARD
+ @ Update SYS_FLAGS with the address that CPU1 will jump to
+ ldr r0, =VE_SYS_FLAGS
+ ldr r1, =CPU1_ENTRY
+ str r1, [r0]
+
+ @ Generate Software Interrupt to wake CPU1 from wfi state
+ ldr r0, =GICD_CTLR
+ ldr r1, =0x01000001
+ str r1, [r0, #0xf00]
+CPU1_ENTRY:
+#endif
#ifdef VEXPRESS
@
@ Program architected timer frequency
@@ -39,7 +53,7 @@ start:
@
@ Set all interrupts to be non-secure
- ldr r0, =0x2c001000 @ Dist GIC base
+ ldr r0, =GICD_CTLR @ Dist GIC base
ldr r1, [r0, #0x04] @ Type Register
cmp r4, #0
andeq r1, r1, #0x1f
@@ -64,7 +78,7 @@ start:
mcr p15, 0, r0, c1, c1, 2
@ Leave monitor.S trap in place for the transition...
- mov r0, #0xf0000000
+ ldr r0, =monitor
mcr p15, 0, r0, c12, c0, 1 @ Monitor vector base address
@ Set up hvbar so hvc comes back here.
@@ -100,13 +114,19 @@ into_hyp_mode:
@
@ Secondary CPUs (following the RealView SMP booting protocol)
@
+#ifdef BOARD
+ @ Clear SYS_FLAGS to let the kernel wake CPU1 properly
+ ldr r0, =VE_SYS_FLAGS
+ ldr r1, =0xffffffff
+ str r1, [r0, 0x04]
+#endif
- ldr r1, =fs_start - 0x100
+ ldr r1, =monitor - 0x100
adr r2, 1f
ldmia r2, {r3 - r7} @ move the code to a location
stmia r1, {r3 - r7} @ less likely to be overridden
#ifdef VEXPRESS
- ldr r0, =0x1c010030 @ VE SYS_FLAGS register
+ ldr r0, =VE_SYS_FLAGS @ VE SYS_FLAGS register
#else
ldr r0, =0x10000030 @ RealView SYS_FLAGS register
#endif
@@ -122,6 +142,7 @@ into_hyp_mode:
#endif
2:
+#ifndef BOARD
@
@ UART initialisation (38400 8N1)
@
@@ -174,3 +195,31 @@ kernel_cmd:
.asciz KCMD
#endif
kernel_cmd_end:
+#else /* BOARD */
+run_kernel:
+ @
+ @ Kernel parameters
+ @
+ mov r0, #0
+ ldr r1, =2272 @ Versatile Express
+ adr r2, atags
+ mov r3, #0
+ ldr lr, =kernel
+ mov pc, lr @ jump to the kernel
+
+atags:
+ @ ATAG_CORE
+ .long 2
+ .long 0x54410001
+
+ @ ATAG_CMDLINE
+ .long (1f - .) >> 2
+ .long 0x54410009
+ /* The kernel boot command line is defined in config.mk */
+ .asciz KCMD
+ .align 2
+1:
+ @ ATAG_NONE
+ .long 0
+ .long 0x00000000
+#endif /* BOARD */
diff --git a/model.lds.S b/model.lds.S
index 07fae8c..af3f326 100644
--- a/model.lds.S
+++ b/model.lds.S
@@ -21,8 +21,8 @@ INPUT(./uImage)
PHYS_OFFSET = 0x80000000;
-MON_OFFSET = 0xf0000000;
-STACKTOP = 0xff000000;
+MON_OFFSET = 0xff800000;
+STACKTOP = 0xfff00000;
SECTIONS
@@ -47,6 +47,7 @@ SECTIONS
. = MON_OFFSET;
+ monitor = .;
.monitor : { monitor.o }
/* Put most of the actual boot loader code up in high memory
--
1.7.9.5
