Get aarch64 hello world working

$ m=aarch64-tiny
    $ make -j8 m=$m o/$m/tool/hello/hello.com o/third_party/qemu/qemu-aarch64
    $ o/third_party/qemu/qemu-aarch64 o/$m/tool/hello/hello.com
    hello world
    $ ls -hal o/$m/tool/hello/hello.com
    -rwxr-xr-x 1 jart jart 4.0K May  9 05:04 o/aarch64-tiny/tool/hello/hello.com

build/config.mk

@@ -18,7 +18,7 @@ TARGET_ARCH ?= -msse3
 endif
 
 ifeq ($(MODE), aarch64)
-CONFIG_CCFLAGS += -O2  # $(BACKTRACES) $(FTRACE)
+CONFIG_CCFLAGS += -O2 $(BACKTRACES) #$(FTRACE)
 CONFIG_CPPFLAGS += -DSYSDEBUG
 endif
 
@@ -32,7 +32,7 @@ endif
 #   - Limited Backtraces
 #   - Compiles 28% faster
 #
-ifeq ($(MODE),fastbuild)
+ifeq ($(MODE), fastbuild)
 CONFIG_CCFLAGS += $(BACKTRACES) $(FTRACE) -O
 CONFIG_CPPFLAGS += -DSYSDEBUG -DDWARFLESS
 CONFIG_OFLAGS += -g0
@@ -185,6 +185,31 @@ PYFLAGS +=				\
 	-B
 endif
 
+ifeq ($(MODE), aarch64-tiny)
+CONFIG_CPPFLAGS +=			\
+	-DTINY				\
+	-DNDEBUG			\
+	-DTRUSTWORTHY
+CONFIG_CCFLAGS +=			\
+	-Os				\
+	-fno-align-functions		\
+	-fno-align-jumps		\
+	-fno-align-labels		\
+	-fno-align-loops		\
+	-fschedule-insns2		\
+	-fomit-frame-pointer		\
+	-momit-leaf-frame-pointer	\
+	-foptimize-sibling-calls	\
+	-DDWARFLESS
+CONFIG_OFLAGS +=			\
+	-g0
+CONFIG_LDFLAGS +=			\
+	-S
+PYFLAGS +=				\
+	-O2				\
+	-B
+endif
+
 # Linux-Only Tiny Mode
 #
 #   - `make MODE=tinylinux`

build/definitions.mk

@@ -56,6 +56,7 @@ TMPDIR = o/tmp
 AR = build/bootstrap/ar.com
 CP = build/bootstrap/cp.com
 RM = build/bootstrap/rm.com -f
+GZIP = build/bootstrap/gzip.com
 ECHO = build/bootstrap/echo.com
 TOUCH = build/bootstrap/touch.com
 PKG = build/bootstrap/package.com
@@ -72,13 +73,20 @@ IMAGE_BASE_VIRTUAL ?= 0x400000
 IGNORE := $(shell $(ECHO) -2 ♥cosmo)
 IGNORE := $(shell $(MKDIR) o/tmp)
 
+ifneq ($(findstring aarch64,$(MODE)),)
+ARCH = aarch64
+VM = o/third_party/qemu/qemu-aarch64
+else
+ARCH = x86_64
+endif
+
 ifneq ("$(wildcard o/third_party/gcc/bin/x86_64-pc-linux-gnu-*)","")
 PREFIX = o/third_party/gcc/bin/x86_64-pc-linux-gnu-
 else
 IGNORE := $(shell build/bootstrap/unbundle.com)
 PREFIX = o/third_party/gcc/bin/x86_64-linux-musl-
 endif
-ifeq ($(MODE), aarch64)
+ifeq ($(ARCH), aarch64)
 PREFIX = o/third_party/gcc/bin/aarch64-linux-musl-
 endif
 
@@ -107,7 +115,7 @@ else
 TMPSAFE = $(TMPDIR)/
 endif
 
-ifneq ($(MODE), aarch64)
+ifneq ($(ARCH), aarch64)
 MNO_FENTRY = -mno-fentry
 endif
 
@@ -115,11 +123,14 @@ FTRACE =								\
 	-pg
 
 BACKTRACES =								\
-	-fno-schedule-insns2						\
 	-fno-omit-frame-pointer						\
 	-fno-optimize-sibling-calls					\
 	-mno-omit-leaf-frame-pointer
 
+ifneq ($(ARCH), aarch64)
+BACKTRACES += -fno-schedule-insns2
+endif
+
 SANITIZER =								\
 	-fsanitize=address
 
@@ -159,7 +170,7 @@ DEFAULT_COPTS =								\
 	-fstrict-overflow						\
 	-fno-semantic-interposition
 
-ifneq ($(MODE), aarch64)
+ifneq ($(ARCH), aarch64)
 DEFAULT_COPTS +=							\
 	-mno-red-zone							\
 	-mno-tls-direct-seg-refs
@@ -197,7 +208,6 @@ DEFAULT_ASFLAGS =							\
 DEFAULT_LDFLAGS =							\
 	-static								\
 	-nostdlib							\
-	-melf_x86_64							\
 	--gc-sections							\
 	--build-id=none							\
 	--no-dynamic-linker						\

build/rules.mk

@@ -32,7 +32,7 @@ o/$(MODE)/%.initabi.o: %.initabi.c ; @$(COMPILE) -AOBJECTIFY.init $(OBJECTIFY.in
 o/$(MODE)/%.ncabi.o: %.ncabi.c     ; @$(COMPILE) -AOBJECTIFY.nc $(OBJECTIFY.ncabi.c) $(OUTPUT_OPTION) $<
 o/$(MODE)/%.real.o: %.c            ; @$(COMPILE) -AOBJECTIFY.real $(OBJECTIFY.real.c) $(OUTPUT_OPTION) $<
 
-ifneq ($(MODE), aarch64)
+ifneq ($(ARCH), aarch64)
 o/%.o: %.s                         ; @$(COMPILE) -AOBJECTIFY.s $(OBJECTIFY.s) $(OUTPUT_OPTION) $<
 o/%.o: o/%.s                       ; @$(COMPILE) -AOBJECTIFY.s $(OBJECTIFY.s) $(OUTPUT_OPTION) $<
 o/%.s: %.S                         ; @$(COMPILE) -APREPROCESS $(PREPROCESS) $(OUTPUT_OPTION) $<
@@ -142,8 +142,8 @@ o/$(MODE)/%: o/$(MODE)/%.com o/$(MODE)/tool/build/cp.com o/$(MODE)/tool/build/as
 # then the stdout/stderr output, which would normally be suppressed,
 # will actually be displayed.
 
-o/$(MODE)/%.runs: o/$(MODE)/%
-	@$(COMPILE) -ACHECK -wtT$@ $< $(TESTARGS)
+o/$(MODE)/%.runs: o/$(MODE)/% $(VM)
+	@$(COMPILE) -ACHECK -wtT$@ $(VM) $< $(TESTARGS)
 
 ################################################################################
 # ELF ZIP FILES

build/run

@@ -0,0 +1,10 @@
+#!/bin/sh
+for last; do true; done
+if printf '%s\n' "$last" | grep aarch64 >/dev/null 2>&1; then
+  if [ ! -f o/third_party/qemu/qemu-aarch64 ]; then
+    make -j8 o/third_party/qemu/qemu-aarch64
+  fi
+  exec o/third_party/qemu/qemu-aarch64 "$@"
+else
+  exec "$@"
+fi