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From: "H. Peter Anvin" <hpa@zytor.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Stefani Seibold <stefani@seibold.net>,
	linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de,
	mingo@redhat.com, ak@linux.intel.com, aarcange@redhat.com,
	john.stultz@linaro.org
Subject: Re: [PATCH] Add VDSO time function support for x86 32-bit kernel
Date: Thu, 13 Dec 2012 16:09:48 -0800	[thread overview]
Message-ID: <50CA6E4C.6000305@zytor.com> (raw)
In-Reply-To: <CALCETrWmYpEh9pLiohF+yu9FnrVfSNdHB_TQOKL6+LkdTF+cVw@mail.gmail.com>

On 12/13/2012 11:32 AM, Andy Lutomirski wrote:
>
> x32's vdso cheats -- x32 code can see high addresses just fine.  The
> toolchain just makes it difficult.
>
> Your best bet is probably to just map the vvar page twice -- once at
> the same address as native 32-bit mode (but only for compat tasks)
> would use and once in the usual fixmap location.  You can't use the
> fixmap for the compat mapping, though, since it would be a *user*
> address.
>
> For HPET support, you'd have to have special support.  I'd say to skip
> it for compat mode.
>

Whatever data you need you can just map it into the vdso range.  There 
really shouldn't be anything special about that at all.

The fixmap stuff is an x86-64 legacy that you don't have to worry about, 
obviously.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.


  reply	other threads:[~2012-12-14  0:10 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-12-12 20:19 [PATCH] Add VDSO time function support for x86 32-bit kernel stefani
2012-12-12 23:34 ` H. Peter Anvin
2012-12-13  5:53   ` Stefani Seibold
2012-12-13  6:10     ` H. Peter Anvin
2012-12-13  6:14     ` H. Peter Anvin
2012-12-13  6:17       ` Stefani Seibold
2012-12-13  6:47         ` H. Peter Anvin
2012-12-13  7:17           ` Stefani Seibold
2012-12-13 19:32             ` Andy Lutomirski
2012-12-14  0:09               ` H. Peter Anvin [this message]
2012-12-14  0:20                 ` Andy Lutomirski
2012-12-14  0:36                   ` H. Peter Anvin
2012-12-14  1:32                   ` H. Peter Anvin
2012-12-14  1:42                     ` Andy Lutomirski
2012-12-14  1:49                       ` H. Peter Anvin
2012-12-14  2:11                         ` Andy Lutomirski
2012-12-14  2:18                           ` H. Peter Anvin
2012-12-14  2:20                             ` Andy Lutomirski
2012-12-14  8:34                               ` [CRIU] " Pavel Emelyanov
2012-12-14 18:35                                 ` H. Peter Anvin
2012-12-14 18:44                                   ` Andy Lutomirski
2012-12-14 18:47                                     ` H. Peter Anvin
2012-12-14 20:12                                       ` Cyrill Gorcunov
2012-12-14 21:08                                         ` H. Peter Anvin
2012-12-14 21:20                                           ` Cyrill Gorcunov
2012-12-14 21:21                                             ` H. Peter Anvin
2012-12-14 21:27                                           ` Andy Lutomirski
2012-12-14 22:00                                             ` H. Peter Anvin
2012-12-14 22:25                                               ` Cyrill Gorcunov
2012-12-14 22:27                                                 ` H. Peter Anvin
2012-12-14 22:43                                                   ` Cyrill Gorcunov
2012-12-14 22:48                                                     ` H. Peter Anvin
2012-12-14 23:48                                                       ` John Stultz
2012-12-14 23:55                                                         ` H. Peter Anvin
2012-12-17  9:05                                     ` Pavel Emelyanov
     [not found]                                       ` <fb2e871b-3e2a-4e96-9eb9-cb2dd4f66eaa@email.android! .com>
2012-12-17 15:21                                       ` H. Peter Anvin
2012-12-17 18:56                                         ` Pavel Emelyanov
2012-12-17 18:57                                           ` H. Peter Anvin
2012-12-14 22:46                                 ` H. Peter Anvin
2012-12-14 23:09                                   ` Stefani Seibold
2012-12-14 23:29                                     ` H. Peter Anvin
  -- strict thread matches above, loose matches on Subject: below --
2012-12-11 16:11 stefani
2012-12-11 19:27 ` John Stultz
2012-12-11 19:37   ` Andy Lutomirski
2012-12-11 20:54   ` Stefani Seibold
2012-12-11 21:18     ` Andy Lutomirski
2012-12-11 21:28       ` Stefani Seibold
2012-12-11 19:37 ` Andy Lutomirski
2012-12-11 20:40   ` Stefani Seibold
2012-12-12  1:29     ` Andy Lutomirski

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