I copied the x86_64 early printk support for plain x86. Is anyone
opposed to me sending this on to Linus?
-- Dave Hansen haveblue@us.ibm.com--------------090302000909010909060003 Content-Type: text/plain; name="early_printk-i386-2.5.47.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="early_printk-i386-2.5.47.patch"
diff -urN linux-2.5.47-clean/arch/i386/Kconfig linux-2.5.47/arch/i386/Kconfig --- linux-2.5.47-clean/arch/i386/Kconfig Sun Nov 10 19:28:05 2002 +++ linux-2.5.47/arch/i386/Kconfig Tue Nov 12 15:19:24 2002 @@ -1574,6 +1574,26 @@ that can still be used by old drivers that are being ported from 2.0/2.2. +config EARLY_PRINTK + bool "Early console support" + default n + depends on DEBUG_KERNEL + help + Write kernel log output directly into the VGA buffer or serial port. + This is useful for kernel debugging when your machine crashes very + early before the console code is initialized. For normal operation + it is not recommended because it looks ugly and doesn't cooperate + with klogd/syslogd or the X server.You should normally N here, + unless you want to debug such a crash. + + Syntax: earlyprintk=vga + earlyprintk=serial[,ttySn[,baudrate]] + Append ,keep to not disable it when the real console takes over. + Only vga or serial at a time, not both. + Currently only ttyS0 and ttyS1 are supported. + Interaction with the standard serial driver is not very good. + The VGA output is eventually overwritten by the real console. + config MAGIC_SYSRQ bool "Magic SysRq key" depends on DEBUG_KERNEL diff -urN linux-2.5.47-clean/arch/i386/kernel/Makefile linux-2.5.47/arch/i386/kernel/Makefile --- linux-2.5.47-clean/arch/i386/kernel/Makefile Sun Nov 10 19:28:05 2002 +++ linux-2.5.47/arch/i386/kernel/Makefile Tue Nov 12 14:57:05 2002 @@ -28,6 +28,7 @@ obj-$(CONFIG_X86_NUMAQ) += numaq.o obj-$(CONFIG_PROFILING) += profile.o obj-$(CONFIG_EDD) += edd.o +obj-$(CONFIG_EARLY_PRINTK) += early_printk.o EXTRA_AFLAGS := -traditional diff -urN linux-2.5.47-clean/arch/i386/kernel/early_printk.c linux-2.5.47/arch/i386/kernel/early_printk.c --- linux-2.5.47-clean/arch/i386/kernel/early_printk.c Wed Dec 31 16:00:00 1969 +++ linux-2.5.47/arch/i386/kernel/early_printk.c Thu Nov 14 11:29:26 2002 @@ -0,0 +1,220 @@ +#include <linux/console.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/string.h> +#include <asm/io.h> + +/* Simple VGA output */ + +#define VGABASE 0xB8000 + +#define MAX_YPOS 25 +#define MAX_XPOS 80 + +static int current_ypos = 1, current_xpos = 0; + +static void early_vga_write(struct console *con, const char *str, unsigned n) +{ + char c; + int i, k, j; + + while ((c = *str++) != '\0' && n-- > 0) { + if (current_ypos >= MAX_YPOS) { + /* scroll 1 line up */ + for(k = 1, j = 0; k < MAX_YPOS; k++, j++) { + for(i = 0; i < MAX_XPOS; i++) { + writew(readw(VGABASE + 2*(MAX_XPOS*k + i)), + VGABASE + 2*(MAX_XPOS*j + i)); + } + } + for(i = 0; i < MAX_XPOS; i++) { + writew(0x720, VGABASE + 2*(MAX_XPOS*j + i)); + } + current_ypos = MAX_YPOS-1; + } + if (c == '\n') { + current_xpos = 0; + current_ypos++; + } else if (c != '\r') { + writew(((0x7 << 8) | (unsigned short) c), + VGABASE + 2*(MAX_XPOS*current_ypos + current_xpos++)); + if (current_xpos >= MAX_XPOS) { + current_xpos = 0; + current_ypos++; + } + } + } +} + +static struct console early_vga_console = { + .name = "earlyvga", + .write = early_vga_write, + .flags = CON_PRINTBUFFER, + .index = -1, +}; + +/* Serial functions losely based on a similar package from Klaus P. Gerlicher */ + +int early_serial_base = 0x3f8; /* ttyS0 */ +#define DEFAULT_BAUD 57600 +#define XMTRDY 0x20 + +#define DLAB 0x80 + +#define TXR 0 /* Transmit register (WRITE) */ +#define RXR 0 /* Receive register (READ) */ +#define IER 1 /* Interrupt Enable */ +#define IIR 2 /* Interrupt ID */ +#define FCR 2 /* FIFO control */ +#define LCR 3 /* Line control */ +#define MCR 4 /* Modem control */ +#define LSR 5 /* Line Status */ +#define MSR 6 /* Modem Status */ +#define DLL 0 /* Divisor Latch Low */ +#define DLH 1 /* Divisor latch High */ + + +static int early_serial_putc(unsigned char ch) +{ + unsigned timeout = 0xffff; + while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) + rep_nop(); + outb(ch, early_serial_base + TXR); + return timeout ? 0 : -1; +} + +static void early_serial_write(struct console *con, const char *s, unsigned n) +{ + while (*s && n-- > 0) { + early_serial_putc(*s); + if (*s == '\n') + early_serial_putc('\r'); + s++; + } +} + +static __init void early_serial_init(char *opt) +{ + unsigned char c; + unsigned divisor, baud = DEFAULT_BAUD; + char *s, *e; + + if (*opt == ',') + ++opt; + + s = strsep(&opt, ","); + if (s != NULL) { + unsigned port; + if (!strncmp(s,"0x",2)) + early_serial_base = simple_strtoul(s, &e, 16); + else { + static int bases[] = { 0x3f8, 0x2f8 }; + if (!strncmp(s,"ttyS",4)) + s+=4; + port = simple_strtoul(s, &e, 10); + if (port > 1 || s == e) + port = 0; + early_serial_base = bases[port]; + } + } + + outb(0x3, early_serial_base + LCR); /* 8n1 */ + outb(0, early_serial_base + IER); /* no interrupt */ + outb(0, early_serial_base + FCR); /* no fifo */ + outb(0x3, early_serial_base + MCR); /* DTR + RTS */ + + s = strsep(&opt, ","); + if (s != NULL) { + baud = simple_strtoul(s, &e, 0); + if (baud == 0 || s == e) + baud = DEFAULT_BAUD; + } + + divisor = 115200 / baud; + c = inb(early_serial_base + LCR); + outb(c | DLAB, early_serial_base + LCR); + outb(divisor & 0xff, early_serial_base + DLL); + outb((divisor >> 8) & 0xff, early_serial_base + DLH); + outb(c & ~DLAB, early_serial_base + LCR); +} + +static struct console early_serial_console = { + .name = "earlyser", + .write = early_serial_write, + .flags = CON_PRINTBUFFER, + .index = -1, +}; + +/* Direct interface for emergencies */ +struct console *early_console = &early_vga_console; +static int early_console_initialized = 0; + +void early_printk(const char *fmt, ...) +{ + char buf[512]; + int n; + va_list ap; + va_start(ap,fmt); + n = vsnprintf(buf,512,fmt,ap); + early_console->write(early_console,buf,n); + va_end(ap); +} + +static int keep_early; + +int __init setup_early_printk(char *opt) +{ + char *space; + char buf[256]; + + if (early_console_initialized) + return -1; + + strncpy(buf,opt,256); + buf[255] = 0; + space = strchr(buf, ' '); + if (space) + *space = 0; + + if (strstr(buf,"keep")) + keep_early = 1; + + if (!strncmp(buf, "serial", 6)) { + early_serial_init(buf + 6); + early_console = &early_serial_console; + } else if (!strncmp(buf, "ttyS", 4)) { + early_serial_init(buf); + early_console = &early_serial_console; + } else if (!strncmp(buf, "vga", 3)) { + early_console = &early_vga_console; + } else { + early_console = NULL; + return -1; + } + early_console_initialized = 1; + register_console(early_console); + early_printk( "early printk console registered\n" ); + return 0; +} + +void __init disable_early_printk(void) +{ + if (!early_console_initialized || !early_console) + return; + if (!keep_early) { + printk("disabling early console...\n"); + unregister_console(early_console); + early_console_initialized = 0; + } else { + printk("keeping early console.\n"); + } +} + +/* syntax: earlyprintk=vga + earlyprintk=serial[,ttySn[,baudrate]] + Append ,keep to not disable it when the real console takes over. + Only vga or serial at a time, not both. + Currently only ttyS0 and ttyS1 are supported. + Interaction with the standard serial driver is not very good. + The VGA output is eventually overwritten by the real console. */ +__setup("earlyprintk=", setup_early_printk); diff -urN linux-2.5.47-clean/arch/i386/kernel/setup.c linux-2.5.47/arch/i386/kernel/setup.c --- linux-2.5.47-clean/arch/i386/kernel/setup.c Sun Nov 10 19:28:13 2002 +++ linux-2.5.47/arch/i386/kernel/setup.c Thu Nov 14 11:15:22 2002 @@ -84,6 +84,7 @@ extern void early_cpu_init(void); extern void dmi_scan_machine(void); +extern void setup_early_printk(char *); extern int root_mountflags; extern char _text, _etext, _edata, _end; extern int blk_nohighio; @@ -836,7 +837,12 @@ void __init setup_arch(char **cmdline_p) { unsigned long max_low_pfn; + char* s; + s = strstr(saved_command_line, "earlyprintk="); + if (s != NULL) + setup_early_printk(s+12); + pre_setup_arch_hook(); early_cpu_init();
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