| Message ID | 20160404193803.GK351@pd.tnic (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Apr 4, 2016 at 12:38 PM, Borislav Petkov <bp@alien8.de> wrote: > On Mon, Apr 04, 2016 at 06:00:42PM +0200, Peter Zijlstra wrote: >> On Mon, Apr 04, 2016 at 08:32:21AM -0700, Andy Lutomirski wrote: >> >> > Adding locking would be easy enough, wouldn't it? >> >> See patch in this thread.. >> >> > But do any platforms really boot a second CPU before switching to real >> > printk? >> >> I _only_ use early_printk() as printk() is a quagmire of fail :-) > > And since I'm the king of minimalistic changes... this below > works. However, the problem is that we need to pull up all that > early_param parsing in order to enable the early console, i.e. > "earlyprintk=ttyS0,115200" cmdline parsing. > > And we can do all that after having setup the IDT. So I'd need to do > some early dancing with cmdline_find_option_bool(boot_command_line, ... > in asm or so. Need to think about it more. > I'd be nervous about moving early param parsing, especially as part of the same patch. Could you do it by moving just the earlyprintk stuff a la fpu__init_parse_early_param()? --Andy
On Mon, Apr 04, 2016 at 02:31:46PM -0700, Andy Lutomirski wrote: > Could you do it by moving just the earlyprintk stuff a la > fpu__init_parse_early_param()? Yeah, something like that. I'll play with this more tomorrow. Btw, no need to make any of this part of your patchset - I'd like early changes like that to cook longer for obvious reasons anyway...
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 1f4422d5c8d0..ad534226653b 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -130,6 +130,13 @@ static void __init copy_bootdata(char *real_mode_data) } } +static int _early_printk(const char *fmt, va_list args) +{ + early_printk(fmt, args); + + return 0; +} + asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) { int i; @@ -164,6 +171,10 @@ 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)); + parse_early_param(); + this_cpu_write(printk_func, _early_printk); + + printk("This is a test!\n"); /* * Load microcode early on BSP. diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 2367ae07eb76..998d6c675549 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -882,6 +882,7 @@ void __init setup_arch(char **cmdline_p) */ __flush_tlb_all(); #else + this_cpu_write(printk_func, vprintk_default); printk(KERN_INFO "Command line: %s\n", boot_command_line); #endif diff --git a/include/linux/printk.h b/include/linux/printk.h index 9ccbdf2c1453..97df81c97b2f 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -169,6 +169,7 @@ void __init setup_log_buf(int early); __printf(1, 2) void dump_stack_set_arch_desc(const char *fmt, ...); void dump_stack_print_info(const char *log_lvl); void show_regs_print_info(const char *log_lvl); +int vprintk_default(const char *fmt, va_list args); #else static inline __printf(1, 0) int vprintk(const char *s, va_list args)