From: "H. Peter Anvin" <hpa@zytor.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>,
David Miller <davem@davemloft.net>,
"Theodore Ts'o" <tytso@mit.edu>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
Network Development <netdev@vger.kernel.org>,
"linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH] x86: make DR*_RESERVED unsigned long
Date: Wed, 24 Apr 2013 18:20:33 -0700 [thread overview]
Message-ID: <517884E1.5060404@zytor.com> (raw)
In-Reply-To: <CAFTL4hyCQ1DGg5JOmWgvZoC9kcrV6TmodCw=TCFcr+QXMwv9yQ@mail.gmail.com>
On 04/24/2013 04:31 PM, Frederic Weisbecker wrote:
>>
>> Now, DR6 is a bit special in that a bunch of the reserved bits are
>> hardwired to 1, not 0; I don't know offhand if that is true for bits
>> [63:32].
>
> Hmm, good point, could it be a problem given that we clear the
> reserved dr6 bits on do_trap() and write that 'cleaned up" value back
> to "tsk->thread.debugreg6"? Probably not if those hardwired reserved
> bits are set to "1" on dr6 physical write whether those bits are
> cleared or not in their storage in thread struct before resuming the
> task?
>
OK, the SDM states that DR6[63:32] are reserved and must be written as
zero (not one).
So the quiescent 64-bit value of DR6 is 0x0000_0000_FFFF_0FF0.
-hpa
next prev parent reply other threads:[~2013-04-25 1:20 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CA+55aFwpLu0qNms=hkQr43yqD0K9DgESNm91OEWKT1ZuT8MU6Q@mail.gmail.com>
2013-04-23 0:23 ` Unsigned widening casts of binary "not" operations Linus Torvalds
2013-04-23 8:59 ` David Laight
2013-04-23 8:59 ` David Laight
2013-04-23 14:29 ` Linus Torvalds
2013-04-23 15:24 ` David Laight
2013-04-23 15:24 ` David Laight
2013-04-23 15:42 ` Linus Torvalds
2013-04-23 15:52 ` Theodore Ts'o
2013-04-23 16:05 ` Linus Torvalds
2013-04-23 17:37 ` David Miller
2013-04-23 17:52 ` Linus Torvalds
2013-04-23 17:56 ` David Miller
2013-04-23 18:21 ` Linus Torvalds
2013-04-24 12:36 ` Geert Uytterhoeven
2013-04-23 0:32 ` H. Peter Anvin
2013-04-23 13:00 ` Theodore Ts'o
2013-04-24 7:26 ` Ingo Molnar
2013-04-24 7:47 ` Cyrill Gorcunov
2013-04-25 1:13 ` Lin Ming
2013-04-24 17:07 ` [PATCH] x86: make DR*_RESERVED unsigned long Oleg Nesterov
2013-04-24 18:45 ` H. Peter Anvin
2013-04-25 14:48 ` Oleg Nesterov
2013-04-26 16:38 ` [PATCH v2] " Oleg Nesterov
2013-04-26 16:44 ` H. Peter Anvin
2013-04-26 17:15 ` Oleg Nesterov
2013-04-27 14:45 ` Oleg Nesterov
2013-04-27 16:20 ` H. Peter Anvin
2013-04-28 0:58 ` Frederic Weisbecker
2013-04-28 17:27 ` Oleg Nesterov
2013-04-28 17:32 ` H. Peter Anvin
2013-04-28 17:39 ` Oleg Nesterov
2013-04-28 17:43 ` H. Peter Anvin
2013-04-24 22:48 ` [PATCH] " Frederic Weisbecker
2013-04-24 23:06 ` H. Peter Anvin
2013-04-24 23:31 ` Frederic Weisbecker
2013-04-25 1:20 ` H. Peter Anvin [this message]
2013-04-26 14:20 ` [tip:perf/core] perf/x86/intel/P4: Robistify P4 PMU types tip-bot for Ingo Molnar
2013-04-26 16:13 ` Borislav Petkov
2013-04-26 16:24 ` Cyrill Gorcunov
2013-04-26 16:39 ` Borislav Petkov
2013-04-26 16:46 ` Cyrill Gorcunov
2013-04-27 16:14 ` Borislav Petkov
2013-04-27 16:33 ` Cyrill Gorcunov
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=517884E1.5060404@zytor.com \
--to=hpa@zytor.com \
--cc=a.p.zijlstra@chello.nl \
--cc=davem@davemloft.net \
--cc=fweisbec@gmail.com \
--cc=gorcunov@gmail.com \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=oleg@redhat.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=tytso@mit.edu \
--cc=x86@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.