Re: [PATCH -v4] x86: Setup early console as early as possible inx86_start_kernel()

From: H. Peter Anvin
Date: Mon Oct 11 2010 - 14:38:33 EST


On 10/11/2010 10:58 AM, Yinghai Lu wrote:
>
> #ifdef CONFIG_X86_TRAMPOLINE
> Index: linux-2.6/arch/x86/kernel/head64.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/head64.c
> +++ linux-2.6/arch/x86/kernel/head64.c
> @@ -74,6 +74,10 @@ void __init x86_64_start_kernel(char * r
> /* clear bss before set_intr_gate with early_idt_handler */
> clear_bss();
>
> + /* boot_params is in bss */
> + copy_bootdata(__va(real_mode_data));
> + setup_early_console();
> +
> /* Make NULL pointers segfault */
> zap_identity_mappings();
>
> @@ -97,7 +101,14 @@ void __init x86_64_start_kernel(char * r
>
> void __init x86_64_start_reservations(char *real_mode_data)
> {
> - copy_bootdata(__va(real_mode_data));
> + /*
> + * hdr.version is always not 0, so check it to see
> + * if boot_params is copied or not.
> + */
> + if (!boot_params.hdr.version) {
> + copy_bootdata(__va(real_mode_data));
> + setup_early_console();
> + }
>
> memblock_init();
>

Under what conditions would we *not* have gotten through
x86_64_start_kernel()?

-hpa
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