linux-kernel - Re: [PATCH] x86, efi: change name of efi_no_storage_paranoia parameter to efi_storage

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Message-ID: <1385027623.6516.4090.camel@linux-s257.site>
Date:	Thu, 21 Nov 2013 17:53:43 +0800
From:	joeyli <jlee@...e.com>
To:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Cc:	Madper Xie <cxie@...hat.com>,
	Matt Fleming <matt@...sole-pimps.org>,
	Richard Weinberger <richard@....at>, linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org, matt.fleming@...el.com,
	matthew.garrett@...ula.com
Subject: Re: [PATCH] x86, efi: change name of efi_no_storage_paranoia
 parameter to efi_storage_paranoia

於 四，2013-11-21 於 18:13 +0900，Yasuaki Ishimatsu 提到：
> (2013/11/20 17:08), joeyli wrote:
> > 於 三，2013-11-20 於 15:26 +0900，Yasuaki Ishimatsu 提到：
> >> (2013/11/19 12:16), Madper Xie wrote:
> >>>
> >>> isimatu.yasuaki@...fujitsu.com writes:
> >>>
> >>>> Hi Matt,
> >>>>
> >>>> Sorry for late the reply.
> >>>>
> >>>>
> >>>> (2013/11/11 19:54), Matt Fleming wrote:
> >>>>> On Mon, 11 Nov, at 05:52:59PM, Yasuaki Ishimatsu wrote:
> >>>>>> Hi Matt,
> >>>>>>
> >>>>>> I uses FUJITSU's x86 box.
> >>>>>> This does not become bricked even if I use all efi variable storage.
> >>>>>> Thus I want a way to not need to specify efi_no_storage_paranoia
> >>>>>> parameter.
> >>>>>
> >>>>> The efi_no_storage_paranoia parameter was introduced because some
> >>>>> machines do not initiate garbage collection of the NVRAM until you
> >>>>> allocate all space - basically it's a switch to turn off the "save 5KB
> >>>>> of stoarge at all times" workaround that is needed to avoid bricking
> >>>>> some machines.
> >>>>>
> >>>>> The intention of the switch is not to allow you to fill your NVRAM just
> >>>>> because you can. If that is something you want to do then I think it's
> >>>>> fair to require you to explicitly turn on efi_no_storage_paranoia. But
> >>>>> I'm assuming here that you are doing something like writing lots and
> >>>>> lots of pstore entries and just want to write as many as your variable
> >>>>> storage will allow? Or are you doing something more fundamental like
> >>>>> creating BootXXXX entries?
> >>>>>
> >>>>> What are you doing to run into the 5KB reserve? How much NVRAM does your
> >>>>> machine come with?
> >>>>
> >>>> I just add boot entry to NVRAM by efibootmgr command. But when Linux boots up,
> >>>> the remaining NVRAM is less than 5Kbyte. So I cannnot add new entry.
> >>>>
> >>> Howdy Yasuaki,
> >>>     If the remaining NVRAM is less than 5Kb, your writing will trigger a
> >>>     NVRAM storage reclamation. However you still failed creating entry. So
> >>>     I'm just curious what itmes occupy lots of nvram storage space.
> >>
> >> Even if we got EFI_OUT_OF_RESOURCES while running Linux, gc does not run.
> >> Trigger of gc is when EFI_OUT_OF_RESOURCES occurs on pre OS environment with
> >> UEFI. So on my system, if EFI_OUT_OF_RESOURCES occurs by the 5Kbyte threshold,
> >> we cannot use nvram storage until EFI_OUT_OF_RESOURCES occurs on pre OS
> >> environment with UEFI.
> >>
> >> Thanks,
> >> Yasuaki Ishimatsu
> >
> > Can we try to trigger gc by EFI_OUT_OF_RESOURCE in EFI stub kernel or
> > EFI boot loader to recover NVRAM space? Does work with the BIOS on this
> > machine?
> 
> Yes. I can trigger gc by EFI_OUT_OF_RESOUCE in EFI shell on my machine.
> 
> Thanks,
> Yasuaki Ishimatu
> 

OK, then maybe can try to trigger gc in EFI stub before
ExitBootService(). 

Another problem is what's the reasonable threshold. The threshold should
bigger then 5Kbyte, then we write a dummy BootTime NV variable to
trigger gc.


Thanks
Joey Lee

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