linux-kernel - Re: Shorten efi regions output

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Date:	Wed, 21 Jan 2015 00:48:58 -0500
From:	Jon Masters <jonathan@...masters.org>
To:	Laszlo Ersek <lersek@...hat.com>,
	Matt Fleming <matt@...sole-pimps.org>,
	Borislav Petkov <bp@...en8.de>
CC:	Dave Young <dyoung@...hat.com>,
	linux-efi <linux-efi@...r.kernel.org>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Matt Fleming <matt.fleming@...el.com>,
	Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: Shorten efi regions output

On 1/5/15, 10:00 AM, Laszlo Ersek wrote:
> On 01/05/15 15:03, Matt Fleming wrote:
>> On Wed, 10 Dec, at 11:46:28AM, Borislav Petkov wrote:
>>> On Wed, Dec 10, 2014 at 10:17:41AM +0800, Dave Young wrote:
>>>> I have same feeling with you, it is too long for most of people.
>>>>
>>>> Since the printk code are for EFI_DEBUG, they are around the #ifdef
>>>> so I would like to see a kernel param like efi_debug=on, so only
>>>> efi_debug is specified then these verbose messages are printed.
>>>> Without the param kernel can print some basic infomation about the
>>>> memory ranges.
>>>>
>>>> In arm64 code there's already a uefi_debug param it can be moved to
>>>> general code so that there will be a goable switch.
>>>
>>> Hmm, makes sense to me. Maybe we should really hide those behind a
>>> debug switch, the question is whether asking the user to boot with
>>> "efi_debug=on" in order to see the regions is ok. And I think it is ok
>>> because we do that when debugging other stuff so I don't see anything
>>> different here.
>>>
>>> And then when they're disabled by default, we don't really need to
>>> shorten them as they're pure debug output then.
>>>
>>> Matt?
>>
>> I'm fine with disabling the EFI memory output regions by default.
>>
>> Printing the regions is still useful for debugging, but like you
>> mention, we frequently ask users to enable other debug options when
>> tracking down issues.
>>
>> Laszlo, would you be OK with that?
>
> Sure.

Pardon my intrusion into this thread (just going over the past month's 
LKML for things I missed). I'd like to see some map output by default in 
the kernel. We have on a number of occasions found just this output 
useful in debugging boot issues on ARM servers and I suspect that will 
remain the case over the coming months. Sure, you can always tell 
someone to reboot, but then you have to rely on them doing it.

Jon.

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