linux-kernel - Re: [PATCH 1/2] x86, setup: reorgize the early_console

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Date:	Mon, 02 Aug 2010 13:30:17 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Cyrill Gorcunov <gorcunov@...il.com>
CC:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Pekka Enberg <penberg@...helsinki.fi>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] x86, setup: reorgize the early_console_setup

On 08/02/2010 01:17 PM, Cyrill Gorcunov wrote:
> On Mon, Aug 02, 2010 at 12:23:17PM -0700, Yinghai Lu wrote:
>> On 08/02/2010 08:09 AM, Cyrill Gorcunov wrote:
>>> On Mon, Aug 02, 2010 at 12:13:31AM -0700, Yinghai Lu wrote:
>> So try to include string.c/printf.c/cmdline.c/early_serial_console.c in arch/x86/boot/compressed/misc.c
>> and analyze that command line again.
>>
>> then kexec path will get support too. that is from arch/x86/boot/compressed/head_32.S or head_64.S, startup_32.
>> and skip arch/x86/boot/main.c
>>
>> later with following patch for 3, we get all covered in c code.
>> 1. arch/x86/boot/main.c: setup code.
>> 2. arch/x86/boot/compressed/misc.c: decompress_kernel code : the 2 -v3 patches that i sent last night.
>> 3. arch/x86/kernel/head64.c: real kernel.
>>
>>
>> [PATCH -v2] x86: Setup early console as early as possible
>>
>> Analyze "console=uart8250,io,0x3f8,115200n8" in i386_start_kernel/x86_64_start_kernel,
>> and call setup_early_serial8250_console() to init early serial console.
>>
>> only can handle io port kind of 8250. because mmio need ioremap.
>>
>> -v2: use boot_params.hdr.version instead of adding another variable, Suggested by hpa
>>      update after using x86 memblock patchset
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>> ---

> ...
>   
>> +	/* make sure if it is copied already */
>> +	if (boot_params.hdr.version)
>> +		return;
>> +
> 
> And Yinghai, lets be more verbose here a bit, since for those who will
> be reading this code later might be non-obvious why we have checked for
> 'version' here. I guess something like "an easy way to check if boot_params
> were already copied". Actually it's clean from commit message but I think
> we first read code comments and commit messages after, agreed? ;-)

will change to 

        /*
         * hdr.version is always not 0, so check it to see
         *  if boot_params is copied or not.
         */

will resend this patch after memblock x86 changes.

YH
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