From mboxrd@z Thu Jan 1 00:00:00 1970 From: Austin S Hemmelgarn Subject: Re: [PATCH] rtc: Disable EFI rtc for x86 Date: Mon, 10 Nov 2014 11:45:06 -0500 Message-ID: <5460EB92.1090501@gmail.com> References: <1412339576-17972-1-git-send-email-matt@console-pimps.org> <20141109182231.GA29337@pd.tnic> <1415618533.14686.239.camel@mfleming-mobl1.ger.corp.intel.com> <201411101723.49197@pali> Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms020105030201000609040506" Return-path: In-Reply-To: <201411101723.49197@pali> Sender: linux-kernel-owner@vger.kernel.org To: =?UTF-8?B?UGFsaSBSb2jDoXI=?= , Matt Fleming Cc: Borislav Petkov , Mark Salter , Alessandro Zummo , rtc-linux@googlegroups.com, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, Dave Young , "H. Peter Anvin" , Matthew Garrett List-Id: linux-efi@vger.kernel.org This is a cryptographically signed message in MIME format. --------------ms020105030201000609040506 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable 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? >>> >>> Sounds like we need an efi=3Drtc_enable knob for people who >>> what to use it... >> >> 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. >> >> 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. > > 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. > I can also confirm that it works correctly on a number of ASUS and=20 ASrock desktop motherboards with the most recent BIOS updates, and on a=20 Lenovo Thinkpad L540. I can however confirm that it DOES NOT work=20 however on an Acer Aspire V5-131 system, though I had never updated the=20 BIOS on that one, so it may work correctly with a newer BIOS version. > Maybe problems which were reported are only specific for 32bit > UEFI? Or 32bit kernels? > > And I think that if I know that efi time service working on > machine, I should be able to use it with mainline kernel (without > hacking Kconfig to enable it and so...). > I agree, without it you need PC CMOS RTC support to access the RTC on=20 most systems, which in turn means that you have to enable the CSM in the = EFI firmware, which is annoying cause you can't easily dual boot windows = with secure boot when the CSM is enabled. --------------ms020105030201000609040506 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIFuDCC BbQwggOcoAMCAQICAw9gVDANBgkqhkiG9w0BAQ0FADB5MRAwDgYDVQQKEwdSb290IENBMR4w HAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBIENlcnQgU2lnbmlu ZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2FjZXJ0Lm9yZzAeFw0xNDA4 MDgxMTMwNDRaFw0xNTAyMDQxMTMwNDRaMGMxGDAWBgNVBAMTD0NBY2VydCBXb1QgVXNlcjEj MCEGCSqGSIb3DQEJARYUYWhmZXJyb2luN0BnbWFpbC5jb20xIjAgBgkqhkiG9w0BCQEWE2Fo ZW1tZWxnQG9oaW9ndC5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDdmm8R BM5D6fGiB6rpogPZbLYu6CkU6834rcJepfmxKnLarYUYM593/VGygfaaHAyuc8qLaRA3u1M0 Qp29flqmhv1VDTBZ+zFu6JgHjTDniBii1KOZRo0qV3jC5NvaS8KUM67+eQBjm29LhBWVi3+e a8jLxmogFXV0NGej+GHIr5zA9qKz2WJOEoGh0EfqZ2MQTmozcGI43/oqIYhRj8fRMkWXLUAF WsLzPQMpK19hD8fqwlxQWhBV8gsGRG54K5pyaQsjne7m89SF5M8JkNJPH39tHEvfv2Vhf7EM Y4WGyhLAULSlym1AI1uUHR1FfJaj3AChaEJZli/AdajYsqc7AgMBAAGjggFZMIIBVTAMBgNV HRMBAf8EAjAAMFYGCWCGSAGG+EIBDQRJFkdUbyBnZXQgeW91ciBvd24gY2VydGlmaWNhdGUg Zm9yIEZSRUUgaGVhZCBvdmVyIHRvIGh0dHA6Ly93d3cuQ0FjZXJ0Lm9yZzAOBgNVHQ8BAf8E BAMCA6gwQAYDVR0lBDkwNwYIKwYBBQUHAwQGCCsGAQUFBwMCBgorBgEEAYI3CgMEBgorBgEE AYI3CgMDBglghkgBhvhCBAEwMgYIKwYBBQUHAQEEJjAkMCIGCCsGAQUFBzABhhZodHRwOi8v b2NzcC5jYWNlcnQub3JnMDEGA1UdHwQqMCgwJqAkoCKGIGh0dHA6Ly9jcmwuY2FjZXJ0Lm9y Zy9yZXZva2UuY3JsMDQGA1UdEQQtMCuBFGFoZmVycm9pbjdAZ21haWwuY29tgRNhaGVtbWVs Z0BvaGlvZ3QuY29tMA0GCSqGSIb3DQEBDQUAA4ICAQCr4klxcZU/PDRBpUtlb+d6JXl2dfto OUP/6g19dpx6Ekt2pV1eujpIj5whh5KlCSPUgtHZI7BcksLSczQbxNDvRu6LNKqGJGvcp99k cWL1Z6BsgtvxWKkOmy1vB+2aPfDiQQiMCCLAqXwHiNDZhSkwmGsJ7KHMWgF/dRVDnsl6aOQZ jAcBMpUZxzA/bv4nY2PylVdqJWp9N7x86TF9sda1zRZiyUwy83eFTDNzefYPtc4MLppcaD4g Wt8U6T2ffQfCWVzDirhg4WmDH3MybDItjkSB2/+pgGOS4lgtEBMHzAGQqQ+5PojTHRyqu9Jc O59oIGrTaOtKV9nDeDtzNaQZgygJItJi9GoAl68AmIHxpS1rZUNV6X8ydFrEweFdRTVWhUEL 70Cnx84YBojXv01LYBSZaq18K8cERPLaIrUD2go+2ffjdE9ejvYDhNBllY+ufvRizIjQA1uC OdktVAN6auQob94kOOsWpoMSrzHHvOvVW/kbokmKzaLtcs9+nJoL+vPi2AyzbaoQASVZYOGW pE3daA0F5FJfcPZKCwd5wdnmT3dU1IRUxa5vMmgjP20lkfP8tCPtvZv2mmI2Nw5SaXNY4gVu WQrvkV2in+TnGqgEIwUrLVbx9G6PSYZZs07czhO+Q1iVuKdAwjL/AYK0Us9v50acIzbl5CWw ZGj3wjGCA6EwggOdAgEBMIGAMHkxEDAOBgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6 Ly93d3cuY2FjZXJ0Lm9yZzEiMCAGA1UEAxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEh MB8GCSqGSIb3DQEJARYSc3VwcG9ydEBjYWNlcnQub3JnAgMPYFQwCQYFKw4DAhoFAKCCAfUw GAYJKoZIhvcNAQkDMQsGCSqGSIb3DQEHATAcBgkqhkiG9w0BCQUxDxcNMTQxMTEwMTY0NTA2 WjAjBgkqhkiG9w0BCQQxFgQUKmYW/BnaBA096zNa5fSzHQUxKPIwbAYJKoZIhvcNAQkPMV8w XTALBglghkgBZQMEASowCwYJYIZIAWUDBAECMAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIA gDANBggqhkiG9w0DAgIBQDAHBgUrDgMCBzANBggqhkiG9w0DAgIBKDCBkQYJKwYBBAGCNxAE MYGDMIGAMHkxEDAOBgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0 Lm9yZzEiMCAGA1UEAxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJ ARYSc3VwcG9ydEBjYWNlcnQub3JnAgMPYFQwgZMGCyqGSIb3DQEJEAILMYGDoIGAMHkxEDAO BgNVBAoTB1Jvb3QgQ0ExHjAcBgNVBAsTFWh0dHA6Ly93d3cuY2FjZXJ0Lm9yZzEiMCAGA1UE AxMZQ0EgQ2VydCBTaWduaW5nIEF1dGhvcml0eTEhMB8GCSqGSIb3DQEJARYSc3VwcG9ydEBj YWNlcnQub3JnAgMPYFQwDQYJKoZIhvcNAQEBBQAEggEAzLFP31mZJKW5KprL4Wu63TBHZIFz 5nsgL+rE6vPAd9S6RO2b1NIwzba0HZwS8Y8bQGHNMDRQvoXXyEAXhTDThaVVhFjg6JihAGer zvsaDbIC5ulw7ELLLMCTe07w4REYuL9nkMTFmQmy7nNVH79Zg6hhFgo6yAtTDhMcJhen7ehe kyG7isljUHws4xbEGRr1Y1WKwCF3X/ikEcgRjZK5kHHL6i5QSfASM2EY1ForKxjgi6yBr80w ea6Bgj4ETP1aSdIRFo1MQeyPuIuBOv1uN5OPIk+N8bDEhckTwGkE6uFnQ+OOvisv2S8Em1xk 3BpduT/dRT6ZDp/Y7G+a21jWBgAAAAAAAA== --------------ms020105030201000609040506--