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From: Yinghai Lu on 15 Jul 2010 18:40

to save the early_serial_base.

Also bootloader could fill that field, so setup code could reuse it.

decompress code could reuse early serial console from setup code.

Signed-off-by: Yinghai Lu <yinghai(a)kernel.org>

---
Documentation/x86/zero-page.txt | 1 +
arch/x86/boot/compressed/misc.c | 25 +++++++++++++++++++++++++
arch/x86/boot/tty.c | 7 ++++++-
arch/x86/include/asm/bootparam.h | 3 ++-
4 files changed, 34 insertions(+), 2 deletions(-)

Index: linux-2.6/Documentation/x86/zero-page.txt
===================================================================
--- linux-2.6.orig/Documentation/x86/zero-page.txt
+++ linux-2.6/Documentation/x86/zero-page.txt
@@ -12,6 +12,7 @@ Offset Proto Name Meaning
000/040 ALL screen_info Text mode or frame buffer information
(struct screen_info)
040/014 ALL apm_bios_info APM BIOS information (struct apm_bios_info)
+054/002 ALL serial_console_port_base early serial console preset
058/008 ALL tboot_addr Physical address of tboot shared page
060/010 ALL ist_info Intel SpeedStep (IST) BIOS support information
(struct ist_info)
Index: linux-2.6/arch/x86/boot/compressed/misc.c
===================================================================
--- linux-2.6.orig/arch/x86/boot/compressed/misc.c
+++ linux-2.6/arch/x86/boot/compressed/misc.c
@@ -125,6 +125,11 @@ static void error(char *m);
*/
static struct boot_params *real_mode; /* Pointer to real-mode data */
static int quiet;
+static int early_serial_base;
+
+#define XMTRDY 0x20
+#define TXR 0 /* Transmit register (WRITE) */
+#define LSR 5 /* Line Status */

void *memset(void *s, int c, size_t n);
void *memcpy(void *dest, const void *src, size_t n);
@@ -170,6 +175,16 @@ static void scroll(void)
vidmem[i] = ' ';
}

+static void serial_putchar(int ch)
+{
+ unsigned timeout = 0xffff;
+
+ while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
+ cpu_relax();
+
+ outb(ch, early_serial_base + TXR);
+}
+
static void __putstr(int error, const char *s)
{
int x, y, pos;
@@ -179,6 +194,14 @@ static void __putstr(int error, const ch
if (!error)
return;
#endif
+ if (early_serial_base) {
+ const char *str = s;
+ while (*str) {
+ if (*str == '\n')
+ serial_putchar('\r');
+ serial_putchar(*str++);
+ }
+ }

if (real_mode->screen_info.orig_video_mode == 0 &&
lines == 0 && cols == 0)
@@ -319,6 +342,8 @@ asmlinkage void decompress_kernel(void *
lines = real_mode->screen_info.orig_video_lines;
cols = real_mode->screen_info.orig_video_cols;

+ early_serial_base = real_mode->serial_console_port_base;
+
free_mem_ptr = heap; /* Heap */
free_mem_end_ptr = heap + BOOT_HEAP_SIZE;

Index: linux-2.6/arch/x86/boot/tty.c
===================================================================
--- linux-2.6.orig/arch/x86/boot/tty.c
+++ linux-2.6/arch/x86/boot/tty.c
@@ -266,8 +266,13 @@ static void parse_console_uart8250(void)

void console_init(void)
{
- parse_earlyprintk();
+ early_serial_base = boot_params.serial_console_port_base;
+
+ if (!early_serial_base)
+ parse_earlyprintk();

if (!early_serial_base)
parse_console_uart8250();
+
+ boot_params.serial_console_port_base = early_serial_base;
}
Index: linux-2.6/arch/x86/include/asm/bootparam.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/bootparam.h
+++ linux-2.6/arch/x86/include/asm/bootparam.h
@@ -93,7 +93,8 @@ struct efi_info {
struct boot_params {
struct screen_info screen_info; /* 0x000 */
struct apm_bios_info apm_bios_info; /* 0x040 */
- __u8 _pad2[4]; /* 0x054 */
+ __u16 serial_console_port_base; /* 0x054 */
+ __u8 _pad2[2]; /* 0x056 */
__u64 tboot_addr; /* 0x058 */
struct ist_info ist_info; /* 0x060 */
__u8 _pad3[16]; /* 0x070 */
--
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