commit f56312c5ed0e7d6fcc1b7c9a8f7e0e8d34376815
from: Aleksey Ryndin <continue@to.any-key.press>
date: Tue Feb 14 14:44:39 2023 UTC

Add boot code

commit - fb7f0bd881cf45679dafb16895d4efc3a6c4b5f3
commit + f56312c5ed0e7d6fcc1b7c9a8f7e0e8d34376815
blob - e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
blob + 4ddf4f2b5d040e0c877f3ab43fc1db2de20e61e8
--- Makefile
+++ Makefile
@@ -0,0 +1,19 @@
+ARCH		= aarch64
+TARGET		= ${ARCH}-none-elf
+
+CC			= clang
+ASFLAGS		= -target ${TARGET}
+ASRC        = boot.S
+
+OBJS        = ${ASRC:.S=.o}
+
+.PHONY:	clean
+
+all: boot.o
+
+clean:
+	rm -rf *.o
+
+.SUFFIXES: .S.o
+.S.o:
+	${CC} ${ASFLAGS} -c $< -o $@
blob - /dev/null
blob + ce243fcb062a6ae12e8af2c6ef87c94b360c5f60 (mode 644)
--- /dev/null
+++ boot.S
@@ -0,0 +1,27 @@
+.section ".text.boot"
+
+.global _start
+_start:
+    mrs     x0, mpidr_el1
+    and     x0, x0, #0xffffff
+    cbz     x0, _first_processor
+
+    // hang all non primary CPU
+_idle:
+    wfe
+    b       _idle
+
+_first_processor:
+    // zero out BSS section
+    adr     x0, bss_begin
+    adr     x1, bss_end
+_zero_bss:
+    str     xzr, [x0], #8
+    cmp     x0, x1
+    b.lt    _zero_bss
+
+    # set stack before boot code and call kernel
+    adr     x0, _start
+    mov     sp, x0
+    bl      kernel_entry_point
+    b       _idle