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Subject[PATCH] x86: Setup early console as early as possible

Analyze "console=uart8250,io,0x3f8,115200n8" in i386_start_kernel/x86_64_start_kernel,
and call setup_early_serial8250_console() to init early serial console.

only can handle io port kind of 8250. because mmio need ioremap.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
arch/x86/include/asm/setup.h | 1 +
arch/x86/kernel/head.c | 32 ++++++++++++++++++++++++++++++++
arch/x86/kernel/head32.c | 2 ++
arch/x86/kernel/head64.c | 11 +++++++++++
kernel/printk.c | 4 ++++
5 files changed, 50 insertions(+)
Index: linux-2.6/arch/x86/include/asm/setup.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/setup.h
+++ linux-2.6/arch/x86/include/asm/setup.h
@@ -42,6 +42,7 @@ static inline void visws_early_detect(vo
#endif

extern unsigned long saved_video_mode;
+void setup_early_console(void);

extern void reserve_standard_io_resources(void);
extern void i386_reserve_resources(void);
Index: linux-2.6/arch/x86/kernel/head.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/head.c
+++ linux-2.6/arch/x86/kernel/head.c
@@ -53,3 +53,35 @@ void __init reserve_ebda_region(void)
/* reserve all memory between lowmem and the 1MB mark */
reserve_early_overlap_ok(lowmem, 0x100000, "BIOS reserved");
}
+
+#ifdef CONFIG_SERIAL_8250_CONSOLE
+int setup_early_serial8250_console(char *cmdline);
+
+void __init setup_early_console(void)
+{
+ char constr[64], *p, *q;
+
+ /* Can not handle mmio type 8250 uart yet, too early */
+ p = strstr(boot_command_line, "console=uart8250,io,");
+ if (!p)
+ p = strstr(boot_command_line, "console=uart,io,");
+ if (!p)
+ return;
+
+ p += 8; /* sizeof "console=" */
+ q = strchr(p, ' ');
+ if ((q - p) >= sizeof(constr))
+ return;
+
+ memset(constr, 0, sizeof(constr));
+ memcpy(constr, p, q - p);
+
+ lockdep_init();
+
+ setup_early_serial8250_console(constr);
+}
+#else
+void __init setup_early_console(void)
+{
+}
+#endif
Index: linux-2.6/arch/x86/kernel/head32.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/head32.c
+++ linux-2.6/arch/x86/kernel/head32.c
@@ -30,6 +30,8 @@ static void __init i386_default_early_se

void __init i386_start_kernel(void)
{
+ setup_early_console();
+
#ifdef CONFIG_X86_TRAMPOLINE
/*
* But first pinch a few for the stack/trampoline stuff
Index: linux-2.6/arch/x86/kernel/head64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/head64.c
+++ linux-2.6/arch/x86/kernel/head64.c
@@ -41,15 +41,21 @@ static void __init clear_bss(void)
(unsigned long) __bss_stop - (unsigned long) __bss_start);
}

+static int __initdata bootdata_copied;
static void __init copy_bootdata(char *real_mode_data)
{
char * command_line;

+ if (bootdata_copied)
+ return;
+
memcpy(&boot_params, real_mode_data, sizeof boot_params);
if (boot_params.hdr.cmd_line_ptr) {
command_line = __va(boot_params.hdr.cmd_line_ptr);
memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
}
+
+ bootdata_copied = 1;
}

void __init x86_64_start_kernel(char * real_mode_data)
@@ -73,6 +79,10 @@ void __init x86_64_start_kernel(char * r
/* clear bss before set_intr_gate with early_idt_handler */
clear_bss();

+ /* boot_params is in bss */
+ copy_bootdata(__va(real_mode_data));
+ setup_early_console();
+
/* Make NULL pointers segfault */
zap_identity_mappings();

@@ -97,6 +107,7 @@ void __init x86_64_start_kernel(char * r
void __init x86_64_start_reservations(char *real_mode_data)
{
copy_bootdata(__va(real_mode_data));
+ setup_early_console();

reserve_early(__pa_symbol(&_text), __pa_symbol(&__bss_stop), "TEXT DATA BSS");

Index: linux-2.6/kernel/printk.c
===================================================================
--- linux-2.6.orig/kernel/printk.c
+++ linux-2.6/kernel/printk.c
@@ -1203,6 +1203,10 @@ void register_console(struct console *ne
if (console_drivers && newcon->flags & CON_BOOT) {
/* find the last or real console */
for_each_console(bcon) {
+ /* not again */
+ if (bcon == newcon)
+ return;
+
if (!(bcon->flags & CON_BOOT)) {
printk(KERN_INFO "Too late to register bootconsole %s%d\n",
newcon->name, newcon->index);

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