From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pali =?utf-8?q?Roh=C3=A1r?= Subject: Re: [PATCH] rtc: Disable EFI rtc for x86 Date: Fri, 14 Nov 2014 12:21:02 +0100 Message-ID: <201411141221.03260@pali> References: <1412339576-17972-1-git-send-email-matt@console-pimps.org> <201411101723.49197@pali> <5460EB92.1090501@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart3214755.DR6N2d8hxz"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5460EB92.1090501-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Austin S Hemmelgarn Cc: Matt Fleming , Borislav Petkov , Mark Salter , Alessandro Zummo , rtc-linux-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Dave Young , "H. Peter Anvin" , Matthew Garrett List-Id: linux-efi@vger.kernel.org --nextPart3214755.DR6N2d8hxz Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Monday 10 November 2014 17:45:06 Austin S Hemmelgarn wrote: > On 2014-11-10 11:23, Pali Roh=C3=A1r wrote: > > On Monday 10 November 2014 12:22:13 Matt Fleming wrote: > >> On Sun, 2014-11-09 at 19:22 +0100, Borislav Petkov wrote: > >>> On Sun, Nov 09, 2014 at 06:37:46PM +0100, Pali Roh=C3=A1r wrote: > >>>> this patch totally disabled efi rfc driver on x86 > >>>> machines at compile time. But on some x86 machines it > >>>> working without crash and reading from file > >>>> /sys/class/rtc/rtc*/since_epoch returns correct > >>>> information. So why to disable compiling driver on > >>>> machines where driver working? > >>>=20 > >>> Sounds like we need an efi=3Drtc_enable knob for people who > >>> what to use it... > >>=20 > >> I'm not so sure. By and large, the EFI runtime Time > >> services just don't work very well on x86. Just because > >> they work sometimes, doesn't actually mean it's a good > >> idea to use them. > >>=20 > >> The one scenario where the time services are useful is > >> early on during boot when we want to get the timezone > >> information. I have vague recollections of someone working > >> on that. > >=20 > > On laptop Dell Latitude E6440 with 64bit kernel 3.17-rc6 > > (where was rtc-efi.ko enabled at compile time for x86) it > > working fine without crash. So I think that other Dell > > machines could work too. >=20 > I can also confirm that it works correctly on a number of ASUS > and ASrock desktop motherboards with the most recent BIOS > updates, and on a Lenovo Thinkpad L540. I can however > confirm that it DOES NOT work however on an Acer Aspire > V5-131 system, though I had never updated the BIOS on that > one, so it may work correctly with a newer BIOS version. >=20 So how to solve it? I think that something like efi=3Drtc_enable=20 param is better then disabling it for x86 at compile time. Once we figure out which machines are affected or if in future=20 vendors fix their firmwares it can be enabled for new machines... =2D-=20 Pali Roh=C3=A1r pali.rohar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org --nextPart3214755.DR6N2d8hxz Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEABECAAYFAlRl5Z8ACgkQi/DJPQPkQ1KGPgCfen5v4pG31fdM7u0dt1yAdW5B +q8AoJeSNHJqsY8oZ6h4wUu2d1UvZCTs =EqRm -----END PGP SIGNATURE----- --nextPart3214755.DR6N2d8hxz--