[PATCH] x86: early printk handling fixes (99b7de33) · Commits · 戴 / test

The history is that -mm kernels do not work for me for a few months already. The things started from crashing somewhere after starting init, and for the last month - no boot at all, just "Uncompressing... OK, booting kernel", and silence. Early console didn't work too. With the latest releases this degraded into an infinite stream of the "Unknown interrupt or fault" messages. So today my patience ran out and I started to think how can I collect at least some info for the bug-report. Attached is the patch that allows to gather some valueable debug info on the problem by making an early console more useable. I can't properly test the patch, as the kernel still doesn't boot, so I'll explain it in details in a hope someone else can justify the intrusive changes. arch_hooks.h: added prototypes for setup_early_printk() and early_printk(). setup.c: killed wrong setup_early_printk() prototype. Moved setup_early_printk() a bit earlier, as it was not "early enough" to cover the bug I was fighting with. early_printk.c: made it to start printing from the bottom of the screen, otherwise the messages interfere with the ones of the boot-loader, so you can't read them. Signed-off-by:

Stas Sergeev <stsp@aknet.ru> Cc: Andi Kleen <ak@muc.de> Cc: Zwane Mwaikambo <zwane@arm.linux.org.uk> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

arch/i386/kernel/setup.c

+10 −13

Original line number	Diff line number	Diff line
		@@ -1459,6 +1459,16 @@ void __init setup_arch(char **cmdline_p)

		parse_cmdline_early(cmdline_p);

		#ifdef CONFIG_EARLY_PRINTK
		{
		char s = strstr(cmdline_p, "earlyprintk=");
		if (s) {
		setup_early_printk(strchr(s, '=') + 1);
		printk("early console enabled\n");
		}
		}
		#endif

		max_low_pfn = setup_memory();

		/*
		@@ -1483,19 +1493,6 @@ void __init setup_arch(char **cmdline_p)
		* NOTE: at this point the bootmem allocator is fully available.
		*/

		#ifdef CONFIG_EARLY_PRINTK
		{
		char s = strstr(cmdline_p, "earlyprintk=");
		if (s) {
		extern void setup_early_printk(char *);

		setup_early_printk(strchr(s, '=') + 1);
		printk("early console enabled\n");
		}
		}
		#endif


		dmi_scan_machine();

		#ifdef CONFIG_X86_GENERICARCH

arch/x86_64/kernel/early_printk.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -21,7 +21,7 @@
		#define MAX_XPOS max_xpos

		static int max_ypos = 25, max_xpos = 80;
		static int current_ypos = 1, current_xpos = 0;
		static int current_ypos = 25, current_xpos = 0;

		static void early_vga_write(struct console con, const char str, unsigned n)
		{
		@@ -244,6 +244,7 @@ int __init setup_early_printk(char *opt)
		&& SCREEN_INFO.orig_video_isVGA == 1) {
		max_xpos = SCREEN_INFO.orig_video_cols;
		max_ypos = SCREEN_INFO.orig_video_lines;
		current_ypos = max_ypos;
		early_console = &early_vga_console;
		} else if (!strncmp(buf, "simnow", 6)) {
		simnow_init(buf + 6);

include/asm-i386/arch_hooks.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -24,4 +24,7 @@ extern void trap_init_hook(void);
		extern void time_init_hook(void);
		extern void mca_nmi_hook(void);

		extern int setup_early_printk(char *);
		extern void early_printk(const char *fmt, ...) __attribute__((format(printf,1,2)));

		#endif

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