Messages in this thread Patch in this message | | | Date | Wed, 7 Apr 2010 22:44:14 -0700 | Subject | Re: [PATCH v2] x86: Call setup_early_printk before first call to early_printk | From | Yinghai Lu <> |
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On Tue, Apr 6, 2010 at 6:42 PM, Guenter Roeck <guenter.roeck@ericsson.com> wrote: > Current code calls setup_early_printk() too late to catch the initial calls > to early_printk(). This results in those early messages not to be printed on a > serial console. Also, if there is no VGA device in the system, it will cause > bad writes into VGA memory space. This can cause problems if the VGA memory > space is used by another device in such a system. > > Fix the problem by calling setup_early_printk() immediately after the boot > command line is available, and by preventing early_printk() to print anything > before setup_early_printk() was executed. > > Also removed conditional output "Kernel alive". > > Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com> > --- > The first version of this patch used the headline > x86: Do not write to VGA memory space if CONFIG_VGA_CONSOLE is undefined > I changed the headline to reflect its expanded scope. > > I removed the "Kernel alive" message because I don't see how console_loglevel > can ever be equal to 10 when the code is executed. An alternative might be > (if that possibility exists after all) to move it after the call to > setup_early_printk(). > > arch/x86/include/asm/setup.h | 2 ++ > arch/x86/kernel/early_printk.c | 5 ++++- > arch/x86/kernel/head32.c | 4 ++++ > arch/x86/kernel/head64.c | 7 ++++--- > 4 files changed, 14 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h > index 86b1506..83847af 100644 > --- a/arch/x86/include/asm/setup.h > +++ b/arch/x86/include/asm/setup.h > @@ -93,6 +93,8 @@ void *extend_brk(size_t size, size_t align); > : : "i" (sz)); \ > } > > +int __init setup_early_printk(char *buf); > + > #ifdef __i386__ > > void __init i386_start_kernel(void); > diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c > index b9c830c..873f1cd 100644 > --- a/arch/x86/kernel/early_printk.c > +++ b/arch/x86/kernel/early_printk.c > @@ -170,6 +170,9 @@ asmlinkage void early_printk(const char *fmt, ...) > int n; > va_list ap; > > + if (!early_console_initialized) > + return; > +
if someone specify "earlyprintk", early_console will still point to early_vga_console...
prefer to set early_console to NULL,
and here change to
if (!early_console) { printk(fmt, vargs) return; }
> va_start(ap, fmt); > n = vscnprintf(buf, sizeof(buf), fmt, ap); > early_console->write(early_console, buf, n); > @@ -191,7 +194,7 @@ static inline void early_console_register(struct console *con, int keep_early) > register_console(early_console); > } > > -static int __init setup_early_printk(char *buf) > +int __init setup_early_printk(char *buf) > { > int keep; > > diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c > index b2e2460..e2e9c2b 100644 > --- a/arch/x86/kernel/head32.c > +++ b/arch/x86/kernel/head32.c > @@ -30,6 +30,10 @@ static void __init i386_default_early_setup(void) > > void __init i386_start_kernel(void) > { > +#ifdef CONFIG_EARLY_PRINTK > + setup_early_printk(boot_command_line); > +#endif > + > #ifdef CONFIG_X86_TRAMPOLINE > /* > * But first pinch a few for the stack/trampoline stuff > diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c > index 7147143..1b4d6b2 100644 > --- a/arch/x86/kernel/head64.c > +++ b/arch/x86/kernel/head64.c > @@ -88,9 +88,6 @@ void __init x86_64_start_kernel(char * real_mode_data) > } > load_idt((const struct desc_ptr *)&idt_descr); > > - if (console_loglevel == 10) > - early_printk("Kernel alive\n"); > - > x86_64_start_reservations(real_mode_data); > } > > @@ -98,6 +95,10 @@ void __init x86_64_start_reservations(char *real_mode_data) > { > copy_bootdata(__va(real_mode_data)); > > +#ifdef CONFIG_EARLY_PRINTK > + setup_early_printk(boot_command_line); > +#endif
you may need to search "earlyprintk" and cut the "earlyprintk=....." string out at first, and then use that string to call setup_early_printk()
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