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Date:      Mon, 17 Jul 2017 19:43:10 +0300
From:      Konstantin Belousov <kostikbel@gmail.com>
To:        Ian Lepore <ian@freebsd.org>
Cc:        Bruce Evans <brde@optusnet.com.au>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   Re: svn commit: r320901 - in head/sys: amd64/amd64 isa x86/isa
Message-ID:  <20170717164310.GM1935@kib.kiev.ua>
In-Reply-To: <1500308973.22314.89.camel@freebsd.org>
References:  <201707120242.v6C2gvDB026199@repo.freebsd.org> <20170712224803.G1991@besplex.bde.org> <1500308973.22314.89.camel@freebsd.org>

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On Mon, Jul 17, 2017 at 10:29:33AM -0600, Ian Lepore wrote:
> I assumed the reason the efirt code was using the same mutex that
> protected access to the at rtc was because under the hood, the efi rt
> clock is really the same hardware too, accessed via bios code.

EFI spec states it explicitely, e.g. in the description of the GetTime()
function of the Time Services interface:

During runtime, if a PC-AT CMOS device is present in the platform the
caller must synchronize access to the device before calling GetTime().




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