From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: "qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>,
Laurent Vivier <lvivier@redhat.com>,
Peter Crosthwaite <crosthwaitepeter@gmail.com>,
Christopher Covington <cov@codeaurora.org>,
Alistair Francis <alistair.francis@xilinx.com>
Subject: Re: [Qemu-devel] [PATCH] target-arm: Use common CPU cycle infrastructure
Date: Tue, 6 Oct 2015 15:10:21 +0200 [thread overview]
Message-ID: <5613C83D.20908@redhat.com> (raw)
In-Reply-To: <CAFEAcA8z0EMxM4eOPbkRj9VTLGWxbZz_YMFEP6VGZhwSY2qUdg@mail.gmail.com>
On 06/10/2015 15:06, Peter Maydell wrote:
> Looking closer, clock_gettime() also has a userspace
> only fastpath in the VDSO.
Yup, hence the patch that changed the default cpu_get_real_ticks()
implementation to get_clock().
>> > Could we just use CNTVCT_EL0? Which cores have it?
>
> Not guaranteed to be enabled for userspace access by the kernel,
> and even if it is enabled, the kernel folks don't (last time I
> checked) consider this userspace ABI -- it's only there for
> the benefit of the VDSO.
Ok, thanks.
> (CNTVCT_EL0 is how the fast clock_gettime
> and getimeofday paths are implemented.)
Yes.
Paolo
next prev parent reply other threads:[~2015-10-06 13:10 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-30 18:14 [Qemu-devel] [RFC 1/5] arm64: Add PMINTENCLR_EL1 Christopher Covington
2015-04-30 18:14 ` [Qemu-devel] [RFC 2/5] arm64: Add PMOVSCLR_EL0 register Christopher Covington
2015-04-30 18:14 ` [Qemu-devel] [RFC 3/5] arm64: Add PMUSERENR_EL0 register Christopher Covington
2015-04-30 18:14 ` [Qemu-devel] [RFC 4/5] arm64: Unmask PMU bits in debug feature register Christopher Covington
2015-04-30 18:14 ` [Qemu-devel] [RFC 5/5] arm: Simplify cycle counter Christopher Covington
2015-04-30 18:27 ` Peter Maydell
2015-04-30 21:33 ` Christopher Covington
2015-04-30 22:02 ` Peter Maydell
2015-05-04 9:54 ` Paolo Bonzini
2015-05-01 1:24 ` Peter Crosthwaite
2015-05-01 14:35 ` Christopher Covington
2015-05-06 14:05 ` Peter Crosthwaite
2015-05-06 15:38 ` Peter Maydell
2015-09-24 19:43 ` [Qemu-devel] [PATCH] target-arm: Use common CPU cycle infrastructure Christopher Covington
2015-09-28 22:05 ` Alistair Francis
2015-09-29 14:07 ` Christopher Covington
2015-10-02 16:44 ` Christopher Covington
2015-10-02 16:56 ` Peter Maydell
2015-10-02 17:25 ` Peter Crosthwaite
2015-10-02 18:08 ` Peter Maydell
2015-10-02 18:14 ` Peter Crosthwaite
2015-10-02 19:25 ` Christopher Covington
2015-10-02 19:56 ` Peter Crosthwaite
2015-10-02 20:48 ` Christopher Covington
2015-10-02 22:41 ` Peter Maydell
2015-10-05 14:09 ` Paolo Bonzini
2015-10-05 14:11 ` Peter Maydell
2015-10-05 14:27 ` Paolo Bonzini
2015-10-06 12:49 ` Peter Maydell
2015-10-06 12:58 ` Paolo Bonzini
2015-10-06 13:06 ` Peter Maydell
2015-10-06 13:10 ` Paolo Bonzini [this message]
2015-10-13 20:53 ` Peter Maydell
2015-10-14 12:10 ` Christopher Covington
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