From: Matt Fleming <matt@codeblueprint.co.uk>
To: joeyli <jlee@suse.com>
Cc: Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
"Lee, Chun-Yi" <joeyli.kernel@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
x86@kernel.org, linux-efi@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86_64/efi: Mapping Boot and Runtime EFI memory regions to different starting virtual address
Date: Thu, 30 Jul 2015 15:05:42 +0100 [thread overview]
Message-ID: <20150730140542.GI2725@codeblueprint.co.uk> (raw)
In-Reply-To: <20150730133947.GN15651@linux-rxt1.site>
On Thu, 30 Jul, at 09:39:47PM, joeyli wrote:
>
> OK, understood! Thanks for your suggestion!
>
> But, I have a question about mapping Boot Code/Data to -4G area. I understand
> we need Runtime regions, and 1:1 mapping is the workaround of some buggy BIOS.
> But why should kernel mapping Boot regions to -4G area?
We map the Boot Service regions in the -4G area for simplicity, i.e.
it's easier to iterate through the EFI memory map in order, and map
things starting at -4G and working down to lower addresses, than it
would be to make different mapping decisions based on the region type.
As for why we map the Boot Service regions *at all*, that's also a bug
workaround, see commit 916f676f8dc0 ("x86, efi: Retain boot service code
until after switching to virtual mode"). We setup the mappings before we
call efi_free_boot_services().
--
Matt Fleming, Intel Open Source Technology Center
next prev parent reply other threads:[~2015-07-30 14:05 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-30 4:32 [PATCH] x86_64/efi: Mapping Boot and Runtime EFI memory regions to different starting virtual address Lee, Chun-Yi
2015-07-30 4:32 ` Lee, Chun-Yi
[not found] ` <1438230757-30840-1-git-send-email-jlee-IBi9RG/b67k@public.gmane.org>
2015-07-30 7:53 ` H. Peter Anvin
2015-07-30 7:53 ` H. Peter Anvin
[not found] ` <55B9D806.7030705-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
2015-07-30 8:03 ` Borislav Petkov
2015-07-30 8:03 ` Borislav Petkov
[not found] ` <20150730080323.GD8984-K5JNixvcfoxupOikMc4+xw@public.gmane.org>
2015-07-30 10:11 ` Matt Fleming
2015-07-30 10:11 ` Matt Fleming
[not found] ` <20150730101131.GB2725-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-07-30 11:09 ` joeyli
2015-07-30 11:09 ` joeyli
[not found] ` <20150730110959.GJ15651-empE8CJ7fzk2xCFIczX1Fw@public.gmane.org>
2015-07-30 11:18 ` joeyli
2015-07-30 11:18 ` joeyli
[not found] ` <20150730111819.GK15651-empE8CJ7fzk2xCFIczX1Fw@public.gmane.org>
2015-07-30 12:09 ` Matt Fleming
2015-07-30 12:09 ` Matt Fleming
[not found] ` <20150730120916.GD2725-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-07-30 12:31 ` joeyli
2015-07-30 12:31 ` joeyli
2015-07-30 13:17 ` Matt Fleming
[not found] ` <20150730131723.GG2725-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-07-30 13:39 ` joeyli
2015-07-30 13:39 ` joeyli
2015-07-30 14:05 ` Matt Fleming [this message]
[not found] ` <20150730140542.GI2725-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
2015-07-30 14:16 ` joeyli
2015-07-30 14:16 ` joeyli
2015-08-19 16:31 ` Matt Fleming
2015-08-20 1:05 ` joeyli
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