Messages in this thread Patch in this message | | | From | Alexander Kuleshov <> | Subject | [PATCH v9 3/3] x86/earlyprintk: setup earlyprintk as early as possible | Date | Wed, 3 Jun 2015 13:55:41 +0600 |
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The early_printk function is usable only after the setup_early_printk will be executed. We pass 'earlyprintk' through the kernel command line, so it will be usable only after the 'parse_early_param' will be executed. This means that we have usable earlyprintk only during early boot, kernel decompression and after call of the 'parse_early_param'. This patchset makes earlyprintk usable before the call of the 'parse_early_param'.
This patch makes the setup_early_printk visible for head{32,64}.c. So the 'early_printk' function will be usabable after decompression of the kernel and before parse_early_param will be called. It also must be safe if CONFIG_CMDLINE_BOOL and CONFIG_CMDLINE_OVERRIDE are set, because setup_cmdline function will be called before setup_early_printk.
It provides earlyprintk only for serial console, because other needs in ioremap which is not initialized yet.
Tested it with qemu, so early_printk() is usable and prints to serial console right after setup_early_printk function called.
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com> --- arch/x86/include/asm/setup.h | 7 +++++++ arch/x86/kernel/early_printk.c | 30 ++++++++++++++++++++++++++++-- arch/x86/kernel/head32.c | 7 +++++++ arch/x86/kernel/head64.c | 6 ++++++ 4 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h index 59efd0d..201eda0 100644 --- a/arch/x86/include/asm/setup.h +++ b/arch/x86/include/asm/setup.h @@ -120,6 +120,13 @@ asmlinkage void __init x86_64_start_reservations(char *real_mode_data); #endif /* __i386__ */ void __init setup_builtin_cmdline(void); + +#ifdef CONFIG_EARLY_PRINTK +/* used by arch/x86/kernel/head{32,64}.c */ +extern int __init setup_early_serial_console(void); +#else +static inline int __init setup_early_serial_console(void) { return 0; } +#endif /* CONFIG_EARLY_PRINTK */ #endif /* _SETUP */ #else #define RESERVE_BRK(name,sz) \ diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c index 89427d8..5373298 100644 --- a/arch/x86/kernel/early_printk.c +++ b/arch/x86/kernel/early_printk.c @@ -342,14 +342,16 @@ static int __init setup_early_printk(char *buf) keep = (strstr(buf, "keep") != NULL); while (*buf != '\0') { - if (!strncmp(buf, "serial", 6)) { + if (!strncmp(buf, "serial", 6) && + early_serial_console.index == -1) { buf += 6; early_serial_init(buf); early_console_register(&early_serial_console, keep); if (!strncmp(buf, ",ttyS", 5)) buf += 5; } - if (!strncmp(buf, "ttyS", 4)) { + if (!strncmp(buf, "ttyS", 4) && + early_serial_console.index == -1) { early_serial_init(buf + 4); early_console_register(&early_serial_console, keep); } @@ -385,4 +387,28 @@ static int __init setup_early_printk(char *buf) return 0; } +int __init setup_early_serial_console(void) +{ + 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); +} + early_param("earlyprintk", setup_early_printk); diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c index 92e8b5f..6969d97 100644 --- a/arch/x86/kernel/head32.c +++ b/arch/x86/kernel/head32.c @@ -32,6 +32,13 @@ static void __init i386_default_early_setup(void) asmlinkage __visible void __init i386_start_kernel(void) { setup_builtin_cmdline(); + + lockdep_init(); + + setup_early_serial_console(); + + early_printk("Early printk is initialized\n"); + cr4_init_shadow(); sanitize_boot_params(&boot_params); diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 346a042..35dd00f 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -174,6 +174,12 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) setup_builtin_cmdline(); + lockdep_init(); + + setup_early_serial_console(); + + early_printk("Early printk is initialized\n"); + /* * Load microcode early on BSP. */ -- 2.4.0.GIT
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