Update SMP TODO

Makefile

@@ -13,7 +13,7 @@ QEMU ?= qemu-system-i386
 RUN ?= bios_hello_world
 TMP_EXT ?= .tmp
 
-OUTS := $(foreach IN_EXT,$(NASM_EXT) $(GAS_EXT),$(patsubst %$(IN_EXT),%$(OUT_EXT),$(wildcard *$(IN_EXT))))
+OUTS := $(sort $(foreach IN_EXT,$(NASM_EXT) $(GAS_EXT),$(patsubst %$(IN_EXT),%$(OUT_EXT),$(wildcard *$(IN_EXT)))))
 RUN_FILE := $(RUN)$(OUT_EXT)
 
 .PRECIOUS: %$(OBJ_EXT)
@@ -38,14 +38,14 @@ $(COMMON):
 clean:
 	rm -fr *$(OBJ_EXT) *$(OUT_EXT) *$(TMP_EXT)
 
-run: all
+run: $(RUN_FILE)
 	$(QEMU) -drive 'file=$(RUN_FILE),format=raw' -smp 2
 
-debug: all
+debug: $(RUN_FILE)
 	$(QEMU) -hda '$(RUN_FILE)' -S -s &
 	gdb -x gdb.gdb
 
-bochs: all
+bochs: $(RUN_FILE)
 	# Supposes size is already multiples of 512.
 	# We force that with our linker script,
 	# and `grub-mkrescue` also seems to respect it as well.
@@ -59,7 +59,7 @@ bochs: all
 BIG_IMG_DIR := big_img$(TMP_EXT)
 BOOT_DIR := $(BIG_IMG_DIR)/boot
 GRUB_DIR := $(BOOT_DIR)/grub
-big-img: all
+big$(OUT_EXT): all
 	rm -rf '$(BIG_IMG_DIR)'
 	mkdir -p  '$(GRUB_DIR)'
 	for out in $(OUTS); do\
@@ -71,4 +71,4 @@ big-img: all
 	#mkdir -p '$(BOOT_DIR)/multiboot'
 	#printf "menuentry \"multiboot/hello-world\"  {\n   chainloader /boot/multiboot/hello-world.img\n}\n" >> '$(GRUB_DIR)/grub.cfg';\
 	#cp multiboot/hello-world/main.img '$(BOOT_DIR)/multiboot/hello-world.img'
-	grub-mkrescue -o 'big.img' '$(BIG_IMG_DIR)'
+	grub-mkrescue -o '$@' '$(BIG_IMG_DIR)'

TODO.md

@@ -1,7 +1,13 @@
 # TODO
 
--
-    http://stackoverflow.com/questions/1858640/how-can-i-create-a-sleep-function-in-16bit-masm-assembly-x86
+-   SMP sync
+
+    - MONITOR/MWAIT
+    - LOCK prefix
+    - MFENCE
+    - LFENCE
+    - SFENCE
+    - http://stackoverflow.com/a/33651438/895245
 
 -   cache:
 

smp.S

@@ -3,25 +3,7 @@
 
 Expected output: "SMP started"
 
-TODO get working + answer all of:
-
-- http://stackoverflow.com/questions/16364817/assessing-the-apic-and-creating-ipis-in-x86-assembly
-    Closest quesiton so far! Almost there!
-    Table 8-1. Broadcast INIT-SIPI-SIPI Sequence and Choice of Timeouts contains actual code!
-    TODO: how to sleep the right ammount of time?
-- http://stackoverflow.com/questions/15091165/inter-processor-interrupt-usage
-- http://stackoverflow.com/questions/1516530/assembly-and-multicore-cpus?lq=1
-- http://stackoverflow.com/questions/1622388/running-code-on-different-processor-x86-assembly
-- http://stackoverflow.com/questions/26452323/how-can-we-use-multi-core-and-cpu-on-assembly-boot-loader-x86
-- http://stackoverflow.com/questions/2986931/the-way-cores-processes-and-threads-work-exactly?rq=1
-- http://stackoverflow.com/questions/419486/multithreading-and-interrupts
-- http://stackoverflow.com/questions/663958/how-to-control-which-core-a-process-runs-on
-- http://stackoverflow.com/questions/714905/threads-in-x86-assembler-using-the-gnu-assember-as
-- http://stackoverflow.com/questions/7308391/how-is-concurrency-done-in-intel-x86-assembly
-- http://stackoverflow.com/questions/980999/what-does-multicore-assembly-language-look-like
-- http://stackoverflow.com/questions/28047092/by-which-instruction-the-secondary-core-is-triggered-while-starting-the-secondar?rq=1
-- http://stackoverflow.com/questions/23962839/how-to-correctly-use-a-startup-ipi-to-start-an-application-processor?rq=1
-- https://github.com/cirosantilli/oszur11-operating-system-examples/tree/1af6451852887fac3d7206d4d09714c181c81d1e/Chapter_07_Threads
+The hard part is sleeping the right amount of time as required by Intel: this example uses the PIT.
 */
 
 /* Must be a multiple of 0x1000. */
@@ -116,7 +98,11 @@ init:
     xor %ax, %ax
     mov %ax, %ds
     movb $1, SPINLOCK_ADDRESS
-    /* TODO mandatory? Is lock prefix enough? */
+    /*
+    TODO mandatory?
+    - is lock prefix enough?
+    - is caching even on I think not because it is off
+    */
     wbinvd
     hlt
 .equ init_len, . - init

smp.md

@@ -2,15 +2,9 @@
 
 # Symmetric multiprocessing
 
-At fist, a single processor starts.
+Read this first: <http://stackoverflow.com/questions/980999/what-does-multicore-assembly-language-look-like/33651438#33651438>
 
-To start the others, the first processor must tell the APIC to send a few special interrupts to the other processors.
-
-One of those interrupts says where the there processors start running their first instruction from.
-
--   Intel docs: Volume 3, Chapter 8 "Multiple processor Management".
-
-    Does not seem standardized across to AMD.
+-   Does not seem standardized across to AMD.
 
     On Intel goes through the APIC to generate an interrupt across processors:
 
@@ -20,8 +14,6 @@ One of those interrupts says where the there processors start running their firs
 
 -   <https://en.wikipedia.org/wiki/Inter-processor_interrupt>
 
--   Linux kernel `arch/x86/kernel/smpboot.c`
-
 -   newer Intel processors have an L2 shared across cores:
 
     - http://stackoverflow.com/questions/4802565/multiple-threads-and-cpu-cache
@@ -55,19 +47,10 @@ processors on the system bus as the BSP. The remaining processors are designated
 message) from the BSP processor. Upon receiving a SIPI message, an AP executes the BIOS AP configuration code,
 which ends with the AP being placed in halt state.
 
-## AP
+Bibliography:
 
-Application processor: all processors except the boot one.
-
-## ICR
-
-## Interrupt command register
-
-When we write to it, interrupts are sent.
-
-It is memory mapped to `0xFEE0 0300`.
-
-[Intel Manual Volume 3 System Programming Guide - 325384-056US September 2015](https://web.archive.org/web/20151025081259/http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-system-programming-manual-325384.pdf)
-
-- 10.6 "ISSUING INTERPROCESSOR INTERRUPTS" documents its format
-- Table 10-1 Local APIC Register Address Map documents where it is mapped to in memory
+- http://stackoverflow.com/questions/16364817/assessing-the-apic-and-creating-ipis-in-x86-assembly
+- http://stackoverflow.com/questions/980999/what-does-multicore-assembly-language-look-like
+- http://stackoverflow.com/questions/1622388/running-code-on-different-processor-x86-assembly
+- http://stackoverflow.com/questions/1516530/assembly-and-multicore-cpus?lq=1
+- http://stackoverflow.com/questions/663958/how-to-control-which-core-a-process-runs-on