plat/arm: Introduce ARM_LINUX_KERNEL_AS_BL33 build option
Normally, BL33 needs to contain a boot loader like U-Boot or UEFI that
eventually gives control to the OS. However, in some cases, this boot
sequence may be too slow. For example, when doing tests in a
cycle-accurate emulator, the user may only be interested in the
interaction between the Trusted Firmware and the OS, not in the boot
process itself.
The new option ARM_LINUX_KERNEL_AS_BL33 allows BL33 to contain the Linux
kernel image by changing the value of registers x0-x3 to the values
expected by the kernel. This option requires the device tree blob (DTB)
to be present in memory. Its address must be specified in the newly
introduced ARM_PRELOADED_DTB_BASE build option. For now, it only supports
AArch64 kernels.
This option is only available when RESET_TO_BL31=1. For this reason
the BL33 binary must be preloaded in memory and PRELOADED_BL33_BASE must
be used.
For example, if the kernel is loaded at 0x80080000 and the DTB is loaded
at address 0x82000000, the firmware could be built like this:
CROSS_COMPILE=aarch64-linux-gnu- \
make PLAT=fvp DEBUG=1 \
RESET_TO_BL31=1 \
ARM_LINUX_KERNEL_AS_BL33=1 \
PRELOADED_BL33_BASE=0x80080000 \
ARM_PRELOADED_DTB_BASE=0x82000000 \
all fip
Change-Id: If9dc847c65ae2d0c27b51f0fd44fc06b28497db9
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/plat/arm/common/arm_common.mk b/plat/arm/common/arm_common.mk
index 015e454..055819b 100644
--- a/plat/arm/common/arm_common.mk
+++ b/plat/arm/common/arm_common.mk
@@ -80,6 +80,27 @@
$(eval $(call assert_boolean,ARM_XLAT_TABLES_LIB_V1))
$(eval $(call add_define,ARM_XLAT_TABLES_LIB_V1))
+# Don't have the Linux kernel as a BL33 image by default
+ARM_LINUX_KERNEL_AS_BL33 := 0
+$(eval $(call assert_boolean,ARM_LINUX_KERNEL_AS_BL33))
+$(eval $(call add_define,ARM_LINUX_KERNEL_AS_BL33))
+
+ifeq (${ARM_LINUX_KERNEL_AS_BL33},1)
+ ifneq (${ARCH},aarch64)
+ $(error "ARM_LINUX_KERNEL_AS_BL33 is only available in AArch64.")
+ endif
+ ifneq (${RESET_TO_BL31},1)
+ $(error "ARM_LINUX_KERNEL_AS_BL33 is only available if RESET_TO_BL31=1.")
+ endif
+ ifndef PRELOADED_BL33_BASE
+ $(error "PRELOADED_BL33_BASE must be set if ARM_LINUX_KERNEL_AS_BL33 is used.")
+ endif
+ ifndef ARM_PRELOADED_DTB_BASE
+ $(error "ARM_PRELOADED_DTB_BASE must be set if ARM_LINUX_KERNEL_AS_BL33 is used.")
+ endif
+ $(eval $(call add_define,ARM_PRELOADED_DTB_BASE))
+endif
+
# Use an implementation of SHA-256 with a smaller memory footprint but reduced
# speed.
$(eval $(call add_define,MBEDTLS_SHA256_SMALLER))