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From: ebiederm@xmission.com (Eric W. Biederman)
To: "Huang, Ying" <ying.huang@intel.com>
Cc: ak@suse.de, akpm@linux-foundation.org,
	Yinghai Lu <yhlu.kernel@gmail.com>,
	Randy Dunlap <randy.dunlap@oracle.com>,
	Chandramouli Narayanan <mouli@linux.intel.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/5] x86_64 EFI support -v3
Date: Wed, 01 Aug 2007 11:21:59 -0600	[thread overview]
Message-ID: <m1myxbnpag.fsf@ebiederm.dsl.xmission.com> (raw)
In-Reply-To: <1185872127.23149.81.camel@caritas-dev.intel.com> (Ying Huang's message of "Tue, 31 Jul 2007 16:55:27 +0800")

"Huang, Ying" <ying.huang@intel.com> writes:

> On Mon, 2007-07-30 at 22:16 -0600, Eric W. Biederman wrote:
>> "Huang, Ying" <ying.huang@intel.com> writes:
>> > - The variable efi_enabled is used throughout across architecutres if
>> >  CONFIG_EFI option is enabled. The i386 code also uses this variable.
>> >  This is something that can be revisited with code consolidation
>> >  across architectures.
>> 
>> Fix it first. arch/i386/ efi support is horrible, and show what happens
>> when things are not done properly the first time.  Later doesn't happen.
>> With the partvirt logic we have a lot of operations properly split out
>> already.  Figure out how to use them.
>
> What do you suggest to use instead of efi_enabled?
>
> Current method is (efi_enabled based):
>
> (1) Encapsulate EFI based implementation and legacy BIOS based
> implementation into separate functions.
> (2) Define a wrapper function for each interface in (1), efi_enabled is
> used to choose implementation between EFI and legacy BIOS.
>
> Another possible method is (function pointer based):

Exactly.  Which is what everything else in the kernel does and is
extensible.

> 1. Encapsulate EFI based implementation and legacy BIOS based
> implementation into separate functions.

> 2. Define a function pointer for each interface in (1), the function
> pointer is set to legacy BIOS based implementation by default and
> changed to EFI based implementation if appropriate.
>
> Because there are only two possible choice, I think the function pointer
> based method has no big advantages over the efi_enabled based method.

Not at all every hypervisor does these things differently as well,
so in the real world there are a lot of choices. 

Eric

  reply	other threads:[~2007-08-01 17:28 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-07-31  3:12 [PATCH 0/5] x86_64 EFI support -v3 Huang, Ying
2007-07-31  4:16 ` Eric W. Biederman
2007-07-31  8:55   ` Huang, Ying
2007-08-01 17:21     ` Eric W. Biederman [this message]
2007-07-31  4:47 ` Eric W. Biederman
2007-08-06  5:40   ` Huang, Ying
2007-08-08 16:45     ` Eric W. Biederman
2007-08-08 20:41       ` Andi Kleen

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