- A new output binary (board.axf) has been added exclusively for
board usage, which uses a different linker script (board.lds.S).
- BootMonitor has already placed secondary CPUs in wfi state,
generate a software interrupt first and point other cores to
jump to the right location by writing the address to SYS_FLAGS.
- Make room for atags, which are populated from BootMonitor's loader,
at memory address 0x80000100.
- Code relocation for secondary cores in wfe state, has been moved
further back to a safer location than the initrd region.
Usage example in BootMonitor (atags passing idea by Marc Zyngier):
- load zImageDT LOAD_ADRESS 0x80008000
- flash linux boot board earlyprintk console=ttyAMA0 mem=...
Or run the image itself, with default atags being set via config.mk:
- load zImageDT LOAD_ADDRESS 0x80008000
- flash run board
Tested on:
- Dual/single cluster FastModels
- V2P-CA15-TC1 CoreTile
- V2P-CA15-A7-TC2 CoreTile (single cluster and big.LITTLE operation)
Signed-off-by: Alexander Spyridakis <a.spyridakis@xxxxxxxxxxxxxxxxxxxxxx>
---
Makefile | 19 +++++++++---
board.lds.S | 21 +++++++++++++
boot.S | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++---
config-default.mk | 2 +-
4 files changed, 118 insertions(+), 9 deletions(-)
create mode 100644 board.lds.S
diff --git a/Makefile b/Makefile
index 0997dcf..c0f10ca 100644
--- a/Makefile
+++ b/Makefile
@@ -21,8 +21,9 @@ 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
LD = $(CROSS_COMPILE)ld
@@ -31,14 +32,15 @@ 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)
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 $< $@
@@ -49,9 +51,15 @@ $(IMAGE): $(OBJS) model.lds $(KERNEL) $(FILESYSTEM) Makefile
$(SEMIIMG): $(OBJS) modelsemi.lds
$(LD) -o $@ $(OBJS) --script=modelsemi.lds
+$(BOARD): board.o board.lds Makefile
+ $(LD) -o board.axf --script=board.lds
+
boot.o: $(BOOTLOADER)
$(CC) $(CPPFLAGS) -DKCMD='$(KCMD)' -c -o $@ $<
+board.o: $(BOOTLOADER)
+ $(CC) $(CPPFLAGS) -DKCMD='$(KCMD)' -DVE_BOARD -c -o $@ $<
+
%.o: %.c
$(CC) $(CPPFLAGS) -O2 -ffreestanding -I. -Ilibfdt -c -o $@ $<
@@ -61,6 +69,9 @@ 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
diff --git a/board.lds.S b/board.lds.S
new file mode 100644
index 0000000..560f65e
--- /dev/null
+++ b/board.lds.S
@@ -0,0 +1,21 @@
+OUTPUT_FORMAT("elf32-littlearm")
+OUTPUT_ARCH(arm)
+TARGET(binary)
+
+INPUT(./board.o)
+
+PHYS_OFFSET = 0x80000000;
+MON_OFFSET = 0xf0000000;
+
+SECTIONS
+{
+ . = PHYS_OFFSET;
+
+ .text : { board.o }
+
+ . = PHYS_OFFSET + 0x8000;
+ kernel = .;
+
+ . = PHYS_OFFSET + 0x00d00000;
+ fs_start = .;
+}
diff --git a/boot.S b/boot.S
index dd453e3..5d6e6a1 100644
--- a/boot.S
+++ b/boot.S
@@ -12,6 +12,9 @@
.arch_extension virt
.text
+ .equ GICD_CTLR, 0x2c001000
+ .equ VE_SYS_FLAGS, 0x1c010030
+
.macro enter_hyp
@ We assume we're entered in Secure Supervisor mode. To
@ get to Hyp mode we have to pass through Monitor mode
@@ -68,11 +71,60 @@ vectors:
@ ...and return to calling code in NS state
movs pc, lr
-
.globl start
start:
#ifdef SMP
#ifdef VEXPRESS
+#ifdef VE_BOARD
+ @ On the VE board only CPU0 should be awake at this stage
+ @ BootMonitor's linux loader, will pass machine id and atags to r1 and r2
+ @ Save those two registers, instead of passing our own defaults
+ cmp r2, #0
+ ldrne r0, =bootregs
+ stmne r0, {r1, r2}
+
+ @ Update SYS_FLAGS with the address that secondary cores will jump to
+ ldr r0, =VE_SYS_FLAGS
+ ldr r1, =SEC_CORE_ENTRY
+ str r1, [r0]
+
+ @ Generate Software Interrupt to wake secondary cores
+ ldr r0, =GICD_CTLR
+ ldr r1, =(1 << 24)
+ str r1, [r0, #0xf00]
+
+ b SEC_CORE_ENTRY
+
+.org 0x100
+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:
+
+#ifdef USE_INITRD
+ @ ATAG_INITRD2
+ .long 4
+ .long 0x54420005
+ .long fs_start
+ .long FS_SIZE
+#endif
+
+ @ ATAG_NONE
+ .long 0
+ .long 0x00000000
+
+@ BootMonitor will write the atags at 0x80000100, move code as far as we can.
+.org 0xe00
+SEC_CORE_ENTRY:
+#endif
@
@ Program architected timer frequency
@
@@ -95,7 +147,7 @@ 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
@@ -130,12 +182,19 @@ start:
@
enter_hyp
- ldr r1, =fs_start - 0x100
+#ifdef VE_BOARD
+ @ Clear SYS_FLAGS to let the kernel wake the rest of the cores properly
+ ldr r0, =VE_SYS_FLAGS
+ mvn r1, #0
+ str r1, [r0, 0x04]
+#endif
+
+ ldr r1, =MON_OFFSET - 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
@@ -151,6 +210,7 @@ start:
#endif
2:
+#ifndef VE_BOARD
@
@ UART initialisation (38400 8N1)
@
@@ -214,3 +274,20 @@ kernel_cmd:
.asciz KCMD
#endif
kernel_cmd_end:
+#else /* VE_BOARD */
+ enter_hyp
+
+ @
+ @ Kernel parameters
+ @
+ ldr r0, =bootregs
+ ldm r0, {r1, r2}
+ mov r0, #0
+ mov r3, #0
+ ldr lr, =kernel
+ mov pc, lr @ jump to the kernel
+
+bootregs:
+ .long 2272 @ r1
+ .long atags @ r2
+#endif /* VE_BOARD */
diff --git a/config-default.mk b/config-default.mk
index 6c73934..0ba1a06 100644
--- a/config-default.mk
+++ b/config-default.mk
@@ -28,7 +28,7 @@ SYSTEM ?= vexpress
# Turn this on to use an initrd whose contents are in filesystem.cpio.gz
USE_INITRD ?= no
ifeq ($(USE_INITRD),yes)
-CPPFLAGS += -DUSE_INITRD
+CPPFLAGS += -DUSE_INITRD -DFS_SIZE=$(shell stat -c %s $(FILESYSTEM))
FILESYSTEM ?= filesystem.cpio.gz
else
FILESYSTEM =
--
1.7.9.5
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