From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= Subject: Re: Thinkpad X1 Carbon 3rd - Reducing the compressed framebuffer size Date: Wed, 21 Feb 2018 15:28:53 +0200 Message-ID: <20180221132853.GM5453@intel.com> References: <20180206152143.vea6si7ncjj7sxyq@pali> <20180213085030.kiksdi2a7ksae5wz@pali> <20180213132726.GD5453@intel.com> <20180213133842.i5z5jj3sllorsy2w@pali> <20180213153654.GG5453@intel.com> <20180213160437.gy5luyygjvuktuqx@pali> <20180213161221.GK5453@intel.com> <20180213174341.abcjlfjymxbcz25t@pali> <20180213174556.GM5453@intel.com> <20180219093650.avb4xipvflfd2kel@pali> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Content-Disposition: inline In-Reply-To: <20180219093650.avb4xipvflfd2kel@pali> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Pali =?iso-8859-1?Q?Roh=E1r?= Cc: David Airlie , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Rodrigo Vivi List-Id: dri-devel@lists.freedesktop.org T24gTW9uLCBGZWIgMTksIDIwMTggYXQgMTA6MzY6NTBBTSArMDEwMCwgUGFsaSBSb2jDoXIgd3Jv dGU6Cj4gT24gVHVlc2RheSAxMyBGZWJydWFyeSAyMDE4IDE5OjQ1OjU2IFZpbGxlIFN5cmrDpGzD pCB3cm90ZToKPiA+IE9uIFR1ZSwgRmViIDEzLCAyMDE4IGF0IDA2OjQzOjQxUE0gKzAxMDAsIFBh bGkgUm9ow6FyIHdyb3RlOgo+ID4gPiBPbiBUdWVzZGF5IDEzIEZlYnJ1YXJ5IDIwMTggMTg6MTI6 MjEgVmlsbGUgU3lyasOkbMOkIHdyb3RlOgo+ID4gPiA+IE9uIFR1ZSwgRmViIDEzLCAyMDE4IGF0 IDA1OjA0OjM3UE0gKzAxMDAsIFBhbGkgUm9ow6FyIHdyb3RlOgo+ID4gPiA+ID4gU28gaXQgY2Fu IGJlIGRvbmUgb25seSBvbmNlIGFmdGVyIHJlYm9vdD8gT3Igb25seSBwcmlvciB0byBib290aW5n IGtlcm5lbD8KPiA+ID4gPiAKPiA+ID4gPiBOZXZlci4KPiA+ID4gCj4gPiA+IE5ldmVyPyBOb3cg SSdtIGxvc3QuIFdoeSB0aGVuIGRtZXNnIG1lc3NhZ2UgaW5zdHJ1Y3QgdXNlciB0byB0cnkgc2V0 IHVwCj4gPiA+IGl0IGluIEJJT1MgaWYgeW91IHNheSBpdCBpcyBuZXZlciBwb3NzaWJsZT8KPiA+ IAo+ID4gWW91IGNhbiBjaGFuZ2UgaXQgaW4gdGhlIEJJT1MuIE5vIHdheSB0byBjaGFuZ2UgaXQg ZnJvbSB0aGUgb3BlcmF0aW5nIHN5c3RlbS4KPiAKPiBIaSEgQ2FuIHlvdSBleHBsYWluIGl0IGEg Yml0IG1vcmU/Cj4gCj4gV2hhdCBkb2VzIGl0IG1lYW4gImluIEJJT1MiPyBQcmlvciBzd2l0Y2hp bmcgZnJvbSAxNmJpdCByZWFsIG1vZGUgdG8KPiBwcm90ZWN0ZWQgb3IgbG9uZz8gT3IgYmVmb3Jl IGV4aXRpbmcgRUZJIGJvb3Qgc2VydmljZXM/IE9yIGJlZm9yZQo+IGJvb3Rpbmcga2VybmVsICh3 aGVuIGluaXRpYWxpemUgbWVtb3J5IG1hcHBpbmcpPwoKVGhlIEJJT1MgaXMgYSBibGFjayBib3gs IG5vIG9uZSByZWFsbHkga25vd3Mgd2hhdCBpdCdzIGRvaW5nLiBUaGUgc3RvbGVuCm1lbW9yeSBp cyBjYXJ2ZWQgb3V0IHByZXR0eSBlYXJseSBJIHRoaW5rIChhbG9uZ3NpZGUgb3RoZXIgY2FydmVk IG91dApjaHVua3MgZm9yIFNNTSBhbmQgd2hhdG5vdCkuIEFuZCBvbmNlIHRoYXQncyBkb25lIHRo ZSBCSU9TIHVzdWFsbHkgbG9ja3MKZG93biBzdHVmZiBsaWtlIHRoaXMgKHRoZSBodyBoYXMgbWFn aWMgd3JpdGUgb25jZSBsb2NrIGJpdHMgZm9yIHZhcmlvdXMKcmVnaXN0ZXJzKSBzbyB0aGVyZSdz IGp1c3Qgbm8gd2F5IHRvIGNoYW5nZSB0aGluZ3MgYWZ0ZXJ3YXJkcy4KCj4gCj4gSSBzdGlsbCBk byBub3Qgc2VlIHJlYXNvbiBub3IgdW5kZXJzdGFuZCB3aHkgdGhpcyBjYW5ub3QgYmUgcG9zc2li bGUKPiBlaXRoZXIgaW4gYm9vdGxvYWRlciAoZS5nLiBncnViMikgb3IgcHJpb3IgdG8gbG9hZGlu ZyBib290bG9hZGVyIHdoaWNoCj4gcnVucyBpbiBwcm90ZWN0ZWQgb3IgbG9uZyBtb2RlLgo+IAo+ IEl0IGlzIGJlY2F1c2UgQklPUyB1c2VzIHNvbWUgdW5kb2N1bWVudGVkIGNhbGwvcHJvY2VkdXJl IHdoaWNoIHNldHMgdGhhdAo+IGFtb3VudCBvZiBtZW1vcnkgYW5kIGl0IGlzIHVua25vd24gaG93 IHRvIGRvIGl0Pwo+IAo+IC0tIAo+IFBhbGkgUm9ow6FyCj4gcGFsaS5yb2hhckBnbWFpbC5jb20K Ci0tIApWaWxsZSBTeXJqw6Rsw6QKSW50ZWwgT1RDCl9fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fCmRyaS1kZXZlbCBtYWlsaW5nIGxpc3QKZHJpLWRldmVsQGxp c3RzLmZyZWVkZXNrdG9wLm9yZwpodHRwczovL2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9tYWlsbWFu L2xpc3RpbmZvL2RyaS1kZXZlbAo= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936753AbeBUN3D (ORCPT ); Wed, 21 Feb 2018 08:29:03 -0500 Received: from mga14.intel.com ([192.55.52.115]:56866 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933705AbeBUN27 (ORCPT ); Wed, 21 Feb 2018 08:28:59 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,543,1511856000"; d="scan'208";a="19990838" Date: Wed, 21 Feb 2018 15:28:53 +0200 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Pali =?iso-8859-1?Q?Roh=E1r?= Cc: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: Re: Thinkpad X1 Carbon 3rd - Reducing the compressed framebuffer size Message-ID: <20180221132853.GM5453@intel.com> References: <20180206152143.vea6si7ncjj7sxyq@pali> <20180213085030.kiksdi2a7ksae5wz@pali> <20180213132726.GD5453@intel.com> <20180213133842.i5z5jj3sllorsy2w@pali> <20180213153654.GG5453@intel.com> <20180213160437.gy5luyygjvuktuqx@pali> <20180213161221.GK5453@intel.com> <20180213174341.abcjlfjymxbcz25t@pali> <20180213174556.GM5453@intel.com> <20180219093650.avb4xipvflfd2kel@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20180219093650.avb4xipvflfd2kel@pali> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 19, 2018 at 10:36:50AM +0100, Pali Rohár wrote: > On Tuesday 13 February 2018 19:45:56 Ville Syrjälä wrote: > > On Tue, Feb 13, 2018 at 06:43:41PM +0100, Pali Rohár wrote: > > > On Tuesday 13 February 2018 18:12:21 Ville Syrjälä wrote: > > > > On Tue, Feb 13, 2018 at 05:04:37PM +0100, Pali Rohár wrote: > > > > > So it can be done only once after reboot? Or only prior to booting kernel? > > > > > > > > Never. > > > > > > Never? Now I'm lost. Why then dmesg message instruct user to try set up > > > it in BIOS if you say it is never possible? > > > > You can change it in the BIOS. No way to change it from the operating system. > > Hi! Can you explain it a bit more? > > What does it mean "in BIOS"? Prior switching from 16bit real mode to > protected or long? Or before exiting EFI boot services? Or before > booting kernel (when initialize memory mapping)? The BIOS is a black box, no one really knows what it's doing. The stolen memory is carved out pretty early I think (alongside other carved out chunks for SMM and whatnot). And once that's done the BIOS usually locks down stuff like this (the hw has magic write once lock bits for various registers) so there's just no way to change things afterwards. > > I still do not see reason nor understand why this cannot be possible > either in bootloader (e.g. grub2) or prior to loading bootloader which > runs in protected or long mode. > > It is because BIOS uses some undocumented call/procedure which sets that > amount of memory and it is unknown how to do it? > > -- > Pali Rohár > pali.rohar@gmail.com -- Ville Syrjälä Intel OTC