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From: "H. Peter Anvin" <hpa@linux.intel.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Matt Fleming <matt@console-pimps.org>,
	Leif Lindholm <leif.lindholm@linaro.org>,
	Grant Likely <grant.likely@secretlab.ca>,
	Stephen Warren <swarren@wwwdotorg.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	linux-efi@vger.kernel.org,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"patches@linaro.org" <patches@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	matt.fleming@intel.com
Subject: Re: [PATCH 1/4] Documentation: arm: [U]EFI runtime services
Date: Thu, 27 Jun 2013 11:32:49 -0700	[thread overview]
Message-ID: <51CC8551.1090202@linux.intel.com> (raw)
In-Reply-To: <1372257499.2168.5.camel@dabdike>

On 06/26/2013 07:38 AM, James Bottomley wrote:
> On Wed, 2013-06-26 at 14:59 +0100, Matt Fleming wrote:
>> On Wed, 26 Jun, at 03:53:11PM, Leif Lindholm wrote:
>>> It's completely feasible, but we'd need to use a different method to do
>>> the boot services call with a 1:1 mapping (idmap support is not available
>>> until much later in the boot process).
>>
>> At least if you no longer relied upon the idmap we could potentially
>> have a single efi_enter_virtual_mode() call-site in init/main.c, which
>> would be nice.
> 
> The fixed virtual address scheme currently being looked at for x86_64 to
> make SetVirtualAddressMap() kexec invariant doesn't work on 32 bit
> because the address space isn't big enough.  For ARM, given that we've
> much more opportunity to work with the vendors, can we just avoid
> transitioning to a virtual address map and always just install a
> physical mapping before doing efi calls?
> 

What we could do on x86-32 is to map from 0xc0000000 downwards.  It
wouldn't be invariant across kernel builds with different user/kernel
split... but I'm not sure we can win that one.

The other option is to say sod it and just use straight 1:1 mapping on
32 bits...

	-hpa



  parent reply	other threads:[~2013-06-27 18:33 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-06-25 18:10 [PATCH 0/4] arm: [U]EFI runtime services support Leif Lindholm
2013-06-25 18:11 ` [PATCH 1/4] Documentation: arm: [U]EFI runtime services Leif Lindholm
2013-06-25 18:46   ` Christopher Covington
2013-06-25 23:42   ` Stephen Warren
2013-06-26 13:20     ` Grant Likely
2013-06-26 13:53       ` Leif Lindholm
2013-06-26 13:59         ` Matt Fleming
2013-06-26 14:38           ` James Bottomley
2013-06-27  1:32             ` Matthew Garrett
2013-06-27  6:23               ` Grant Likely
2013-06-27  6:33                 ` James Bottomley
2013-06-27 14:37                   ` Matthew Garrett
2013-06-27 15:09                     ` James Bottomley
2013-06-27 15:37                       ` Grant Likely
2013-06-27 17:28                       ` Matthew Garrett
2013-06-27 14:54                   ` Grant Likely
2013-06-27 15:04                     ` James Bottomley
2013-06-27 18:32                       ` Russell King - ARM Linux
2013-06-27  9:00               ` Leif Lindholm
2013-06-27 14:38                 ` Matthew Garrett
2013-06-27 18:32             ` H. Peter Anvin [this message]
2013-06-26 18:32       ` Stephen Warren
2013-06-26 19:31         ` Leif Lindholm
2013-06-27 18:04           ` Stephen Warren
2013-06-27 20:11             ` Grant Likely
2013-06-26 13:13   ` Grant Likely
2013-06-26 14:04     ` Leif Lindholm
2013-06-26 14:35       ` Grant Likely
2013-06-27 14:22     ` Arnd Bergmann
2013-06-30  3:21   ` Rob Landley
2013-06-25 18:11 ` [PATCH 2/4] x86: efi: break efi_lookup_mapped_addr out to generic code Leif Lindholm
2013-06-26 13:30   ` Grant Likely
2013-06-26 13:32   ` Matt Fleming
2013-06-26 14:11     ` Leif Lindholm
2013-06-26 14:40       ` Matt Fleming
2013-06-25 18:11 ` [PATCH 3/4] arm: Add [U]EFI runtime services support Leif Lindholm
2013-06-25 18:20   ` Matthew Garrett
2013-06-26 13:46     ` Grant Likely
2013-06-26 13:46   ` Grant Likely
2013-06-26 13:54     ` Matt Fleming
2013-06-26 14:15       ` Borislav Petkov
2013-06-26 14:35         ` Grant Likely
2013-06-26 14:22     ` Leif Lindholm
2013-06-25 18:11 ` [PATCH 4/4] init: efi: arm: enable (U)EFI runtime services on arm Leif Lindholm
2013-06-26 13:24   ` Grant Likely

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