From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>,
Christopher Covington <cov@codeaurora.org>
Cc: Christoffer Dall <christoffer.dall@linaro.org>,
"cross-distro@lists.linaro.org" <cross-distro@lists.linaro.org>,
Ian Campbell <ian.campbell@citrix.com>,
kvm-devel <kvm@vger.kernel.org>,
Michael Casadevall <Michael.casadevall@linaro.org>,
"marc.zyngier@arm.com" <marc.zyngier@arm.com>,
Rob Herring <rob.herring@linaro.org>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
Stefano Stabellini <stefano.stabellini@citrix.com>,
Grant Likely <grant.likely@linaro.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
arm-mail-list <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC v2] ARM VM System Specification
Date: Tue, 10 Jun 2014 20:56:37 +0200 [thread overview]
Message-ID: <539754E5.3030408@redhat.com> (raw)
In-Reply-To: <CAFEAcA8RttCvbOAw-m-W6C-mh1o4hj6nqGMkDbRsSF6ZoQZ7Kg@mail.gmail.com>
Il 10/06/2014 20:08, Peter Maydell ha scritto:
> On 10 June 2014 18:04, Christopher Covington <cov@codeaurora.org> wrote:
>> On 06/10/2014 10:42 AM, Peter Maydell wrote:
>>> I just noticed that this doesn't mandate that the platform
>>> provides an RTC. As I understand it, the UEFI spec mandates
>>> that there's an RTC (could somebody more familiar with UEFI
>>> than me confirm/deny that?) so we should probably put one here.
>>
>> Pardon my ignorance, but what exactly disqualifies Generic Timer
>> implementations from being used as Real Time Clocks?
>
> So my naive view was that an RTC actually had to have
> support for dealing with real (wall) clock time, ie
> knowing it's 2014 and not 1970. The generic timers are
> just timers. Or am I wrong and UEFI doesn't really
> require that?
The real-time clock provides four UEFI runtime services (GetTime,
SetTime, GetWakeupTime, SetWakeupTime). The spec says that you can
return EFI_DEVICE_ERROR from GetTime/SetTime if "the time could not be
retrieved/set due to a hardware error", but I don't think this is enough
to make these two optional. By comparison, GetWakeupTime/SetWakeupTime
can also return EFI_UNSUPPORTED.
So I agree that the RTC is required in UEFI.
Paolo
WARNING: multiple messages have this Message-ID (diff)
From: pbonzini@redhat.com (Paolo Bonzini)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC v2] ARM VM System Specification
Date: Tue, 10 Jun 2014 20:56:37 +0200 [thread overview]
Message-ID: <539754E5.3030408@redhat.com> (raw)
In-Reply-To: <CAFEAcA8RttCvbOAw-m-W6C-mh1o4hj6nqGMkDbRsSF6ZoQZ7Kg@mail.gmail.com>
Il 10/06/2014 20:08, Peter Maydell ha scritto:
> On 10 June 2014 18:04, Christopher Covington <cov@codeaurora.org> wrote:
>> On 06/10/2014 10:42 AM, Peter Maydell wrote:
>>> I just noticed that this doesn't mandate that the platform
>>> provides an RTC. As I understand it, the UEFI spec mandates
>>> that there's an RTC (could somebody more familiar with UEFI
>>> than me confirm/deny that?) so we should probably put one here.
>>
>> Pardon my ignorance, but what exactly disqualifies Generic Timer
>> implementations from being used as Real Time Clocks?
>
> So my naive view was that an RTC actually had to have
> support for dealing with real (wall) clock time, ie
> knowing it's 2014 and not 1970. The generic timers are
> just timers. Or am I wrong and UEFI doesn't really
> require that?
The real-time clock provides four UEFI runtime services (GetTime,
SetTime, GetWakeupTime, SetWakeupTime). The spec says that you can
return EFI_DEVICE_ERROR from GetTime/SetTime if "the time could not be
retrieved/set due to a hardware error", but I don't think this is enough
to make these two optional. By comparison, GetWakeupTime/SetWakeupTime
can also return EFI_UNSUPPORTED.
So I agree that the RTC is required in UEFI.
Paolo
next prev parent reply other threads:[~2014-06-10 18:56 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-28 18:45 [RFC v2] ARM VM System Specification Christoffer Dall
2014-03-28 18:45 ` Christoffer Dall
2014-03-30 22:10 ` Olof Johansson
2014-03-30 22:10 ` Olof Johansson
2014-03-30 22:10 ` Olof Johansson
2014-03-31 17:26 ` Christoffer Dall
2014-03-31 17:26 ` Christoffer Dall
2014-03-31 17:26 ` Christoffer Dall
2014-04-01 9:49 ` Ian Campbell
2014-04-01 9:49 ` Ian Campbell
2014-04-01 9:49 ` Ian Campbell
2014-04-01 9:57 ` Michael Casadevall
2014-04-01 9:57 ` Michael Casadevall
2014-04-01 9:57 ` Michael Casadevall
2014-04-01 10:16 ` Grant Likely
2014-04-01 10:16 ` Grant Likely
2014-04-01 10:16 ` Grant Likely
2014-04-29 14:42 ` Christoffer Dall
2014-04-29 14:42 ` Christoffer Dall
2014-04-29 14:42 ` Christoffer Dall
2014-04-30 8:14 ` Grant Likely
2014-04-30 8:14 ` Grant Likely
2014-04-30 8:14 ` Grant Likely
2014-06-10 14:42 ` Peter Maydell
2014-06-10 14:42 ` Peter Maydell
2014-06-10 14:42 ` Peter Maydell
2014-06-10 15:03 ` Ian Campbell
2014-06-10 15:03 ` Ian Campbell
2014-06-10 15:03 ` Ian Campbell
2014-06-10 17:00 ` Paolo Bonzini
2014-06-10 17:00 ` Paolo Bonzini
2014-06-10 17:00 ` Paolo Bonzini
2014-06-10 17:04 ` Christopher Covington
2014-06-10 17:04 ` Christopher Covington
2014-06-10 17:04 ` Christopher Covington
2014-06-10 18:08 ` Peter Maydell
2014-06-10 18:08 ` Peter Maydell
2014-06-10 18:08 ` Peter Maydell
2014-06-10 18:56 ` Paolo Bonzini
2014-06-10 18:56 ` Paolo Bonzini [this message]
2014-06-10 18:56 ` Paolo Bonzini
2014-06-10 19:18 ` Paolo Bonzini
2014-06-10 19:18 ` Paolo Bonzini
2014-06-10 19:18 ` Paolo Bonzini
2014-06-10 19:18 ` Paolo Bonzini
2014-06-10 19:18 ` Paolo Bonzini
2014-06-10 19:18 ` Paolo Bonzini
2014-06-11 6:54 ` Christoffer Dall
2014-06-11 6:54 ` Christoffer Dall
2014-06-11 6:54 ` Christoffer Dall
2014-06-11 8:16 ` Paolo Bonzini
2014-06-11 8:16 ` Paolo Bonzini
2014-06-11 8:16 ` Paolo Bonzini
2014-06-11 9:06 ` Arnd Bergmann
2014-06-11 9:06 ` Arnd Bergmann
2014-06-11 9:06 ` Arnd Bergmann
2014-06-30 16:19 ` Jon Masters
2014-06-30 16:19 ` Jon Masters
2014-06-30 16:19 ` Jon Masters
2014-06-30 20:46 ` Christoffer Dall
2014-06-30 20:46 ` Christoffer Dall
2014-06-30 21:14 ` Peter Maydell
2014-06-30 21:14 ` Peter Maydell
2014-06-30 21:14 ` Peter Maydell
2014-07-01 17:03 ` Stefano Stabellini
2014-07-01 17:03 ` Stefano Stabellini
2014-07-01 17:10 ` Peter Maydell
2014-07-01 17:10 ` Peter Maydell
2014-07-01 17:10 ` Peter Maydell
2014-07-02 10:13 ` Christoffer Dall
2014-07-02 10:13 ` Christoffer Dall
2014-07-02 10:13 ` Christoffer Dall
2014-07-01 17:03 ` Stefano Stabellini
2014-06-30 20:46 ` Christoffer Dall
2014-06-11 11:33 ` Grant Likely
2014-06-11 11:33 ` Grant Likely
2014-06-11 11:58 ` Arnd Bergmann
2014-06-11 11:58 ` Arnd Bergmann
2014-06-11 11:58 ` Arnd Bergmann
2014-06-11 12:02 ` Grant Likely
2014-06-11 12:02 ` Grant Likely
2014-06-11 12:02 ` Grant Likely
2014-06-11 14:14 ` Peter Maydell
2014-06-11 14:14 ` Peter Maydell
2014-06-11 14:14 ` Peter Maydell
2014-06-11 11:33 ` Grant Likely
2014-06-10 16:44 ` Claudio Fontana
2014-06-10 16:44 ` Claudio Fontana
2014-06-10 16:44 ` Claudio Fontana
2014-06-10 19:21 ` Arnd Bergmann
2014-06-10 19:21 ` Arnd Bergmann
2014-06-10 19:21 ` Arnd Bergmann
2014-06-11 9:50 ` Stefano Stabellini
2014-06-11 9:50 ` Stefano Stabellini
2014-06-11 9:50 ` Stefano Stabellini
2014-06-11 9:55 ` Christoffer Dall
2014-06-11 9:55 ` Christoffer Dall
2014-06-11 11:28 ` Grant Likely
2014-06-11 11:28 ` Grant Likely
2014-06-11 11:28 ` Grant Likely
2014-06-11 12:04 ` Christoffer Dall
2014-06-11 12:04 ` Christoffer Dall
2014-06-11 12:04 ` Christoffer Dall
2014-06-11 9:55 ` Christoffer Dall
2014-06-11 10:27 ` Arnd Bergmann
2014-06-11 10:27 ` Arnd Bergmann
2014-06-11 10:27 ` Arnd Bergmann
2014-06-11 11:22 ` Grant Likely
2014-06-11 11:22 ` Grant Likely
2014-06-11 11:22 ` Grant Likely
2014-03-28 18:45 Christoffer Dall
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=539754E5.3030408@redhat.com \
--to=pbonzini@redhat.com \
--cc=Michael.casadevall@linaro.org \
--cc=christoffer.dall@linaro.org \
--cc=cov@codeaurora.org \
--cc=cross-distro@lists.linaro.org \
--cc=grant.likely@linaro.org \
--cc=ian.campbell@citrix.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=marc.zyngier@arm.com \
--cc=peter.maydell@linaro.org \
--cc=rob.herring@linaro.org \
--cc=stefano.stabellini@citrix.com \
--cc=xen-devel@lists.xen.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.