[LinuxBIOS] [PATCH] v3: documentation fixes

[Carl-Daniel Hailfinger]

Fix code comments/documentation related to printk.
Sprinkle TODOs all over obviously wrong comments.
Document possible execution flow alternatives for later investigation.

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>

--- 

Index: LinuxBIOSv3/mainboard/adl/msm800sev/stage1.c
===================================================================
--- LinuxBIOSv3/mainboard/adl/msm800sev/stage1.c	(Revision 509)
+++ LinuxBIOSv3/mainboard/adl/msm800sev/stage1.c	(Arbeitskopie)
@@ -51,5 +51,5 @@
 	 */
 	cs5536_disable_internal_uart();
 	w83627hf_enable_serial(0x2e, SERIAL_DEV, SERIAL_IOBASE);
-	printk(BIOS_DEBUG, "Done %s\n", __FUNCTION__);
+	/* We can NOT yet use printk! */
 }
Index: LinuxBIOSv3/mainboard/emulation/qemu-x86/stage1.c
===================================================================
--- LinuxBIOSv3/mainboard/emulation/qemu-x86/stage1.c	(Revision 509)
+++ LinuxBIOSv3/mainboard/emulation/qemu-x86/stage1.c	(Arbeitskopie)
@@ -17,7 +17,7 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  */
 
-/* no printk allowed until hardware is ready; hardware is ready */
+/* no printk allowed until hardware is ready; hardware is not yet ready */
 
 /** 
  * start up hardware needed for stage1
Index: LinuxBIOSv3/lib/stage2.c
===================================================================
--- LinuxBIOSv3/lib/stage2.c	(Revision 509)
+++ LinuxBIOSv3/lib/stage2.c	(Arbeitskopie)
@@ -37,7 +37,10 @@
  *
  * Device Enumeration: in the dev_enumerate() phase.
  *
- * TODO: Check whether this documentation is still correct. Improve it.
+ * TODO:
+ * - Check whether this documentation is still correct. Improve it.
+ * - Replace magic constants by #defines.
+ * - Fix POST codes. Right now phases 1+3 have POST 0x30, phases 2+4 have 0x40.
  */
 int stage2(void)
 {
@@ -54,13 +57,19 @@
 
 	post_code(0x20);
 
-	/* TODO: Explain why we use printk here although it is impossible */
+	/* TODO: Explain why we use printk here although it is claimed to be
+	 * impossible according to the documentation. The "has to be done
+	 * before printk can be used" comment below seems to suggest the same.
+	 * However, we already enable serial in arch/x86/stage1.c:stage1_main()
+	 * when we call hardware_stage1(); uart_init(); console_init(); 
+	 */
 	printk(BIOS_NOTICE, console_test);
 
 	dev_init();
 
 	/* Console init, also ANYTHING that has to be done 
-	 * before printk can be used. 
+	 * before printk can be used.
+	 * FIXME: This comment contradicts the comment above.
 	 */
 	post_code(0x30);
 	dev_phase1();
Index: LinuxBIOSv3/arch/x86/stage1.c
===================================================================
--- LinuxBIOSv3/arch/x86/stage1.c	(Revision 509)
+++ LinuxBIOSv3/arch/x86/stage1.c	(Arbeitskopie)
@@ -108,8 +108,12 @@
 
 	//
 	uart_init();	// initialize serial port
-	console_init(); // print banner
 
+	/* Exactly from now on we can use printk. Celebrate this by printing
+	 * a LB banner.
+	 */
+	console_init();
+
 	if (bist!=0) {
 		printk(BIOS_INFO, "BIST FAILED: %08x", bist);
 		die("");
@@ -133,6 +137,30 @@
 	// FIXME check integrity
 
 
+	/* Right now we have to fit
+	 *   initram stack
+	 *   lar stack
+	 * into cache during CAR. IFF we can be sure that
+	 *   nrv2b stack
+	 *   initram code
+	 *   lar code
+	 * fit into cache as well, we can compress initram code and lar code,
+	 * leading to potential speedup (due to having to read less from ROM)
+	 * and size savings. However, initram code and lar code would have
+	 * to be compiled as PIC code, not as XIP code.
+	 *
+	 * Suggested code flow:
+	 * unrv2b(lar_code);
+	 * ...
+	 * execute_in_car(&archive, "normal/initram");
+	 *
+	 * A less complicated (from a linker perspective) variant would
+	 * compress only initram code, but it is not clear whether all hardware
+	 * can run code from cache while training memory in the area designated
+	 * by the cache. Some processors might drop cache contents in that case,
+	 * rendering the ideas above mostly moot.
+	 * TODO: Check how this works in the real world.
+	 */
 	// find first initram
 	if (check_normal_boot_flag()) {
 		printk(BIOS_DEBUG, "Choosing normal boot.\n");