Make printk() log to a buffer.

Tested on Qemu and Geode LX.
Benefits of this patch:
- printk() now works directly after printk_buffer_init(), even before
the serial port is set up.
- If all you want is a log, you don't have to bother with serial output.
- A payload can read and analyze the log.
- You can build on this and buffer log until serial is available, then
flush the messages buffered so far.

The printk buffer is configurable with a default-on Kconfig variable.

If you want to dump the buffer from the Qemu monitor after CAR has been
disabled, use this command:
memsave 0x90000 65536 memdump.bin

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Peter Stuge <peter@stuge.se>
Acked-by: Stefan Reinauer <stepan@coresystems.de>
Acked-by: Marc Jones <marc.jones@amd.com>


git-svn-id: svn://coreboot.org/repository/coreboot-v3@590 f3766cd6-281f-0410-b1cd-43a5c92072e9

arch/x86/geodelx/stage0.S

@@ -361,6 +361,13 @@ DCacheSetupGood:
 	movw	%ax, %ss
 
 lout:
+#ifdef CONFIG_CONSOLE_BUFFER
+	/* Store pointer to start of printk buffer, should really use
+	 * PRINTK_BUF_ADDR_CAR instead.
+	 */
+	movl    $CONFIG_CARBASE, %eax
+	pushl   %eax  /* printk buffer */
+#endif
 	/* Restore the BIST result. */
 	movl	%ebp, %eax
 

arch/x86/stage0_i586.S

@@ -433,7 +433,13 @@ clear_fixed_var_mtrr_out:
 	movw    %ax, %ss
 
 lout:
-
+#ifdef CONFIG_CONSOLE_BUFFER
+	/* Store pointer to start of printk buffer, should really use
+	 * PRINTK_BUF_ADDR_CAR instead.
+	 */
+	movl    $CONFIG_CARBASE, %eax
+	pushl 	%eax  /* printk buffer */
+#endif
 	/* Restore the BIST result */
 	movl	%ebp, %eax
 	/* We need to set ebp ? No need */

arch/x86/stage1.c

@@ -26,6 +26,7 @@
 #include <tables.h>
 #include <lib.h>
 #include <mc146818rtc.h>
+#include <cpu.h>
 
 /* ah, well, what a mess! This is a hard code. FIX ME but how? 
  * By getting rid of ELF ...
@@ -67,6 +68,12 @@ void init_archive(struct mem_file *archive)
 
 }
 
+void *bottom_of_stack(void)
+{
+	/* -4-4 because CONFIG_CARBASE + CONFIG_CARSIZE - 4 is initial %esp */
+	return (void *)(CONFIG_CARBASE + CONFIG_CARSIZE - 4 - 4);
+}
+
 void dump_mem_range(int msg_level, unsigned char *buf, int size)
 {
 	int i;
@@ -129,6 +136,11 @@ void __attribute__((stdcall)) stage1_main(u32 bist)
 
 	// We have cache as ram running and can start executing code in C.
 
+#ifdef CONFIG_CONSOLE_BUFFER
+	/* Initialize the printk buffer. */
+	printk_buffer_init();
+#endif
+
 	hardware_stage1();
 
 	//
@@ -173,10 +185,14 @@ void __attribute__((stdcall)) stage1_main(u32 bist)
 
 	printk(BIOS_DEBUG, "Done RAM init code\n");
 
-
 	/* Turn off Cache-As-Ram */
 	disable_car();
 
+#ifdef CONFIG_CONSOLE_BUFFER
+	/* Move the printk buffer to PRINTK_BUF_ADDR_RAM */
+	printk_buffer_move((void *)PRINTK_BUF_ADDR_RAM, PRINTK_BUF_SIZE_RAM);
+#endif
+
 	entry = load_file_segments(&archive, "normal/stage2");
 	if (entry == (void *)-1)
 		die("FATAL: Failed loading stage2.");

include/arch/x86/cpu.h

@@ -24,6 +24,7 @@
 
 #include <types.h>
 #include <device/device.h>
+#include <shared.h>
 
 #define X86_VENDOR_INTEL	0
 #define X86_VENDOR_CYRIX	1
@@ -196,4 +197,13 @@ static inline __attribute__((always_inline)) void hlt(void)
 	__asm__ __volatile__("hlt" : : : "memory");
 }
 
+SHARED(bottom_of_stack, void *, void);
+
+#ifdef CONFIG_CONSOLE_BUFFER
+#define PRINTK_BUF_SIZE_CAR (CONFIG_CARSIZE / 2)
+#define PRINTK_BUF_ADDR_CAR CONFIG_CARBASE
+#define PRINTK_BUF_SIZE_RAM 65536
+#define PRINTK_BUF_ADDR_RAM 0x90000
+#endif
+
 #endif /* ARCH_X86_CPU_H */

include/console.h

@@ -37,6 +37,10 @@ void console_tx_flush(void);
 unsigned char console_rx_byte(void);
 int console_tst_byte(void);
 void die(const char *msg);
+#ifdef CONFIG_CONSOLE_BUFFER
+void printk_buffer_init(void);
+void printk_buffer_move(void *newaddr, int newsize);
+#endif
 
 struct console_driver {
 	void (*init)(void);
@@ -46,6 +50,15 @@ struct console_driver {
 	int (*tst_byte)(void);
 };
 
+#ifdef CONFIG_CONSOLE_BUFFER
+struct printk_buffer {
+	int len;
+	int readoffset;
+	int writeoffset;
+	char buffer[];
+};
+#endif
+
 SHARED_WITH_ATTRIBUTES(printk, int, __attribute__((format (printf, 2, 3))),
 					int msg_level, const char *fmt, ...);
 SHARED(banner, void, int msg_level, const char *msg);

lib/Kconfig

@@ -223,5 +223,12 @@ config CONSOLE_PREFIX
 	  When you enable this option, coreboot will prefix each line of
 	  console output with '(LB)'.
 
+config CONSOLE_BUFFER
+	boolean "Console memory buffer support"
+	default y
+	depends CONSOLE
+	help
+	  Save coreboot output in a memory buffer.
+
 endmenu
 

lib/console.c

@@ -3,6 +3,7 @@
 #include <console.h>
 #include <uart8250.h>
 #include <stdarg.h>
+#include <string.h>
 
 int vtxprintf(void (*)(unsigned char, void *arg), 
 		void *arg, const char *, va_list);
@@ -12,8 +13,80 @@ static int console_loglevel(void)
 	return CONFIG_DEFAULT_CONSOLE_LOGLEVEL;
 }
 
+#ifdef CONFIG_CONSOLE_BUFFER
+void printk_buffer_move(void *newaddr, int newsize)
+{
+	struct printk_buffer **p;
+	struct printk_buffer *oldbuf, *newbuf;
+	int copylen;
+	p = bottom_of_stack();
+	oldbuf = *p;
+	newbuf = newaddr;
+	newbuf->len = newsize;
+	newbuf->readoffset = 0;
+	/* Check for wraparound */
+	if (oldbuf->writeoffset < oldbuf->readoffset) {
+		/* Copy from readoffset to end of buffer. */
+		copylen = oldbuf->len - oldbuf->readoffset;
+	} else {
+		/* Copy from readoffset to writeoffset (exclusive).*/
+		copylen = oldbuf->writeoffset - oldbuf->readoffset;
+	}
+	if (copylen > newsize)
+		copylen = newsize;
+	/* If memcpy() ever uses printk we will see pretty explosions. */
+	memcpy(&newbuf->buffer[0], &oldbuf->buffer[oldbuf->readoffset],
+		copylen);
+	newbuf->writeoffset = copylen;
+	/* Check for wraparound */
+	if (oldbuf->writeoffset < oldbuf->readoffset) {
+		/* Copy from start of buffer to writeoffset (exclusive). */
+		copylen = (copylen + oldbuf->writeoffset > newsize)
+				? newsize - copylen : oldbuf->writeoffset;
+		memcpy(&newbuf->buffer[newbuf->writeoffset],
+			&oldbuf->buffer[0], copylen);
+		newbuf->writeoffset += copylen;
+	}
+	*p = newbuf;
+	return;
+}
+
+struct printk_buffer *printk_buffer_addr(void)
+{
+	struct printk_buffer **p;
+	p = bottom_of_stack();
+	return *p;
+}
+
+void printk_buffer_init(void)
+{
+	struct printk_buffer *buf = printk_buffer_addr();
+	buf->len = PRINTK_BUF_SIZE_CAR - sizeof(struct printk_buffer);
+	buf->readoffset = 0;
+	buf->writeoffset = 0;
+	return;
+}
+
+void buffer_tx_byte(unsigned char byte, void *arg)
+{
+	struct printk_buffer *buf = printk_buffer_addr();
+	buf->buffer[buf->writeoffset++] = byte;
+	buf->writeoffset %= buf->len;
+	/* Make sure writeoffset is always ahead of readoffset here. */
+	if (buf->writeoffset == buf->readoffset) {
+		buf->readoffset++;
+		buf->readoffset %= buf->len;
+	}
+	return;
+}
+#endif
+
 void console_tx_byte(unsigned char byte, void *arg)
 {
+#ifdef CONFIG_CONSOLE_BUFFER
+	buffer_tx_byte(byte, arg);
+#endif
+#ifdef CONFIG_CONSOLE_SERIAL
 	if (byte == '\n') {
 		uart8250_tx_byte(TTYSx_BASE, '\r');
 #if defined(CONFIG_CONSOLE_PREFIX) && (CONFIG_CONSOLE_PREFIX == 1)
@@ -26,8 +99,8 @@ void console_tx_byte(unsigned char byte, void *arg)
 		return;
 #endif
 	}
-
 	uart8250_tx_byte(TTYSx_BASE, byte);
+#endif
 }
 
 int printk(int msg_level, const char *fmt, ...)