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, xemul@parallels.com, gorcunov@openvz.org,
andriy.shevchenko@linux.intel.com
Subject: Re: [PATCH 6/6] Add 32 bit VDSO support for 32 and 64 bit kernels
Date: Tue, 18 Dec 2012 14:24:00 -0800 [thread overview]
Message-ID: <50D0ED00.60804@zytor.com> (raw)
In-Reply-To: <CALCETrX2zAA-X7fjoPNSERq0kVDDY43O_u=Oqjq77_ggf64j9A@mail.gmail.com>
On 12/18/2012 12:37 PM, Andy Lutomirski wrote:
>>
>> There is no introduce of new fix address. There are still there for
>> x86_64. If this will currently not a major problem on this architecture
>> than it will not for x86_32 too.
>
> Not necessarily true. On x86-64 (non-compat) the fixmap address is in
> kernel space (high bit set), so it can't conflict with anything in
> user space. On true 32-bit mode, the same applies. In compat mode,
> the fixed address is in *user* space and might conflict with existing
> uses.
>
The other bit is that the fixmap isn't actually fixed on 32 bits, which
creates its own set of problems. As such, I really would prefer a
properly PIC solution.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2012-12-18 22:24 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 [this message]
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
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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