From: "H. Peter Anvin" <hpa@zytor.com>
To: Stefani Seibold <stefani@seibold.net>
Cc: Andy Lutomirski <luto@amacapital.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, xemul@parallels.com, gorcunov@openvz.org,
andriy.shevchenko@linux.intel.com,
Roland McGrath <mcgrathr@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
"H.J. Lu" <hjl.tools@gmail.com>
Subject: Re: [PATCH 6/6] Add 32 bit VDSO support for 32 and 64 bit kernels
Date: Thu, 20 Dec 2012 10:21:07 -0800 [thread overview]
Message-ID: <50D35713.1090506@zytor.com> (raw)
In-Reply-To: <1356025992.25530.1.camel@wall-e>
On 12/20/2012 09:53 AM, Stefani Seibold wrote:
>
> In a 32 bit kernel a VDSO can mapped on an fix address VDSO_HIGH_BASE
> (kernel parameter vdso32=2 or CONFIG_COMPAT_VDSO), which is 0xffffe000.
> There is no available page BEFORE nor AFTER the page, so it is not
> possible to have VVAR or HPET as a part of that list!!!!
>
[Cc: Roland, Linus, H.J.]
The pages before it are safe to use, because they are kernel internal
and hence not ABI (and in fact depend on the kernel configuration
parameters.) So pushing down the start of the fixmap region is not a
problem. This means that to retain this compatibility the existing
entry points need to be at the end, which is more painful than we'd
like, but nevertheless there.
Do we know what actually used these fixed address, if anything, ever?
-hpa
next prev parent reply other threads:[~2012-12-20 18:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-18 9:40 [PATCH 0/6] Add 32 bit VDSO time function support stefani
2012-12-18 9:40 ` [PATCH 1/6] Move out seqcount from seqlock.h stefani
2012-12-18 9:40 ` [PATCH 2/6] Make vsyscall_gtod_data handling x86 generic stefani
2012-12-18 9:40 ` [PATCH 3/6] Make vsyscall_gtod_data compatible with 32 bit VDSO stefani
2012-12-18 9:40 ` [PATCH 4/6] Add new base function _install_special_mapping() to mmap.c stefani
2012-12-18 9:40 ` [PATCH 5/6] Cleanup header files to build a proper 32 bit VDSO stefani
2012-12-18 9:40 ` [PATCH 6/6] Add 32 bit VDSO support for 32 and 64 bit kernels stefani
2012-12-18 16:17 ` H. Peter Anvin
2012-12-18 16:52 ` Stefani Seibold
2012-12-18 18:44 ` H. Peter Anvin
2012-12-18 20:32 ` Stefani Seibold
2012-12-18 20:37 ` Andy Lutomirski
2012-12-18 22:24 ` H. Peter Anvin
2012-12-20 7:41 ` Stefani Seibold
2012-12-20 16:17 ` H. Peter Anvin
2012-12-20 17:53 ` Stefani Seibold
2012-12-20 18:21 ` H. Peter Anvin [this message]
2012-12-20 18:23 ` H.J. Lu
2012-12-20 18:35 ` Roland McGrath
2012-12-20 18:40 ` H. Peter Anvin
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