From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Robin Holt <holt@sgi.com>
Cc: linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@linux.intel.com>
Subject: Re: [PATCH] phys_efi_set_virtual_address_map needs va, no pa.
Date: Wed, 20 Jun 2012 13:07:02 +0100 [thread overview]
Message-ID: <20120620120702.GA3983@srcf.ucam.org> (raw)
In-Reply-To: <20120620082457.GE3464@sgi.com>
On Wed, Jun 20, 2012 at 03:24:57AM -0500, Robin Holt wrote:
> The kernel allocated memmap may end up being beyond the first
> 512GB of memory. That early range is identity mapped, while the
> remainder of memory is not. The net result is the memmap allocated by
> efi_enter_virtual_mode will not be accessible via its __pa as is currently
> passed back to EFI.
>
> Since EFI is going to have to parse the passed in table, I believe the
> EFI documentation is wrong.
>
> I asked one of our BIOS engineers to look at the Intel reference code
> and he said it was obvious that the address would have to be a virtaully
> accessible address as we are in virtual mode while EFI is handling the
> callback.
No, that's completely wrong. UEFI can't be called in virtual mode until
*after* SetVirtualAddressMap(). The UEFI spec indicates that all
physical memory must have an identity mapping at this stage (section
2.3.4), so if we don't then that's a bug that needs to be fixed.
--
Matthew Garrett | mjg59@srcf.ucam.org
next prev parent reply other threads:[~2012-06-20 12:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-20 8:24 [PATCH] phys_efi_set_virtual_address_map needs va, no pa Robin Holt
2012-06-20 12:07 ` Matthew Garrett [this message]
2012-06-20 20:41 ` H. Peter Anvin
2012-06-21 0:27 ` Robin Holt
2012-06-21 0:46 ` H. Peter Anvin
2012-06-21 16:52 ` Robin Holt
2012-06-22 0:35 ` H. Peter Anvin
2012-06-21 19:16 ` Konrad Rzeszutek Wilk
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120620120702.GA3983@srcf.ucam.org \
--to=mjg59@srcf.ucam.org \
--cc=holt@sgi.com \
--cc=hpa@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.