linux-kernel - Re: [PATCH v3] x86: Do not write into VGA memory space if there is no VGA device in the system

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Message-ID: <4BD5A8B7.4050208@zytor.com>
Date:	Mon, 26 Apr 2010 07:52:39 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Pekka Enberg <penberg@...helsinki.fi>
CC:	Guenter Roeck <guenter.roeck@...csson.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH v3] x86: Do not write into VGA memory space if there is
 no 	VGA device in the system

On 04/26/2010 07:35 AM, Pekka Enberg wrote:
>>>
>>> Wouldn't it be better to switch to, say, serial console here to avoid
>>> the NULL check in early_printk()?
>>>
>> This would be another possibility.
>>
>> However, since the serial console was not explicitly selected, it would possibly
>> not be initialized. My understanding is that Peter had a problem with that.
>>
>> One can argue that it would still be better to select the serial console in that case,
>> even though it might not be initialized. Actually, most likely it is (if it exists),
>> since the system must presumably have some means to communicate with the world.
>>
>> I am pretty much open to either option, if that results in the patch being accepted.
>> Just let me know which way to go.
> 
> Peter?

Yes, I really don't want to issue bytes to a serial port that isn't
known to be initialized; it could take a *very* long time even if the
port is actually present, and if the port *isn't* present it could hang
the kernel.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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