linux-kernel - Re: [PATCH] x86, boot: add hex output for debugging

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Message-ID: <5453EDCA.6040406@zytor.com>
Date:	Fri, 31 Oct 2014 13:15:06 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Vivek Goyal <vgoyal@...hat.com>, Andi Kleen <ak@...ux.intel.com>
CC:	Randy Dunlap <rdunlap@...radead.org>,
	Kees Cook <keescook@...omium.org>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	Junjie Mao <eternal.n08@...il.com>
Subject: Re: [PATCH] x86, boot: add hex output for debugging

On 10/31/2014 01:11 PM, Vivek Goyal wrote:
> On Fri, Oct 31, 2014 at 10:42:51AM -0700, Andi Kleen wrote:
>>>> +void __puthex(unsigned long value)
>>>> +{
>>>> +	char alpha[2] = "0";
>>>> +	int bits;
>>>> +	unsigned char byte;
>>>
>>> what is 'byte' for?  (unused)
>>
>> Well the whole function is unused. We don't normally add unused functions
>> to the code because they bitrot too easily.
> 
> I think this is useful. I had to write similar code for printing out
> values during early boot.
> 
> May be we can print some values if CONFIG_X86_VERBOSE_BOOTUP=y.
> That way it will not be an unused code and others can reuse it easily
> to print additional data during debugging.
> 

The various addresses involved in decompression (load address, relocated
address, etc.) might be good ideas.

	-hpa


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