Messages in this thread Patch in this message | | | From | Alexander Kuleshov <> | Subject | [PATCH v5 2/2] x86/earlyprintk: setup earlyprintk as early as possible | Date | Mon, 11 May 2015 16:09:18 +0600 |
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The early_printk function is usable after setup_early_printk will be executed. We pass 'earlyprintk' through the kernel command line. It means that earlyprintk will be usable only after the 'parse_early_param' will be executed. So we have usable earlyprintk only during early boot, kernel decompression and after call of the 'parse_early_param'.
This patch makes setup_early_printk visible for head{32,64}.c So 'early_printk' function will be usabable after decompression of the kernel and before parse_early_param will be called. It also safe if CONFIG_CMDLINE_BOOL and CONFIG_CMDLINE_OVERRIDE are set, because setup_cmdline function will be called before the setup_early_printk.
Tested it with qemu, so early_printk() is usable and prints to serial console right after setup_early_printk function called from arch/x86/kerne/head64.c
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> --- arch/x86/include/asm/serial.h | 2 ++ arch/x86/kernel/early_printk.c | 25 +++++++++++++++++++++++++ arch/x86/kernel/head32.c | 5 +++++ arch/x86/kernel/head64.c | 8 +++++++- 4 files changed, 39 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/serial.h b/arch/x86/include/asm/serial.h index 8378b8c..be3b73a 100644 --- a/arch/x86/include/asm/serial.h +++ b/arch/x86/include/asm/serial.h @@ -26,4 +26,6 @@ { .uart = 0, BASE_BAUD, 0x3E8, 4, STD_COMX_FLAGS }, /* ttyS2 */ \ { .uart = 0, BASE_BAUD, 0x2E8, 3, STD_COM4_FLAGS }, /* ttyS3 */ +int __init setup_early_serial_console(void); + #endif /* _ASM_X86_SERIAL_H */ diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c index 89427d8..d7cc0b1 100644 --- a/arch/x86/kernel/early_printk.c +++ b/arch/x86/kernel/early_printk.c @@ -385,4 +385,29 @@ static int __init setup_early_printk(char *buf) return 0; } +int __init setup_early_serial_console(void) +{ +#ifdef CONFIG_EARLY_PRINTK + char *arg; + + /* + * make sure that we have: + * "serial,0x3f8,115200" + * "serial,ttyS0,115200" + * "ttyS0,115200" + */ + arg = strstr(boot_command_line, "earlyprintk=serial"); + if (!arg) + arg = strstr(boot_command_line, "earlyprintk=ttyS"); + if (!arg) + return -1; + + arg = strstr(boot_command_line, "earlyprintk="); + /* += strlen("earlyprintk"); */ + arg += 12; + + return setup_early_printk(arg); +#endif +} + early_param("earlyprintk", setup_early_printk); diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c index 95eed21..e863ecc 100644 --- a/arch/x86/kernel/head32.c +++ b/arch/x86/kernel/head32.c @@ -32,6 +32,11 @@ static void __init i386_default_early_setup(void) asmlinkage __visible void __init i386_start_kernel(void) { setup_builtin_cmdline(); + setup_early_serial_console(); + + if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG) + early_printk("Kernel alive\n"); + cr4_init_shadow(); sanitize_boot_params(&boot_params); diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index df290d1..905e602 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -28,6 +28,7 @@ #include <asm/bootparam_utils.h> #include <asm/microcode.h> #include <asm/kasan.h> +#include <asm/serial.h> /* * Manage page tables very early on. @@ -171,7 +172,12 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) load_idt((const struct desc_ptr *)&idt_descr); copy_bootdata(__va(real_mode_data)); - setup_builtin_cmdline(); + + setup_builtin_cmdline(); + setup_early_serial_console(); + + if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG) + early_printk("Kernel alive\n"); /* * Load microcode early on BSP. -- 2.4.0
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