From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32D90C433E7 for ; Fri, 9 Oct 2020 12:59:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E0861222C3 for ; Fri, 9 Oct 2020 12:59:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387967AbgJIM7F (ORCPT ); Fri, 9 Oct 2020 08:59:05 -0400 Received: from mx2.suse.de ([195.135.220.15]:36514 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732686AbgJIM7F (ORCPT ); Fri, 9 Oct 2020 08:59:05 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id DF2F2AF80; Fri, 9 Oct 2020 12:59:02 +0000 (UTC) Subject: Re: drmfb console switching problems/questions To: stsp , linux-fbdev@vger.kernel.org, Linux kernel References: <17980f58-c2d2-ac58-88ce-e21b5a56da39@yandex.ru> <70ce31ca-5922-584c-8631-3853c488f3c7@yandex.ru> From: Thomas Zimmermann Message-ID: Date: Fri, 9 Oct 2020 14:58:59 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <70ce31ca-5922-584c-8631-3853c488f3c7@yandex.ru> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="M5HWfsROMBtVeEnVUOr9Di9KQ5NWpqinj" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --M5HWfsROMBtVeEnVUOr9Di9KQ5NWpqinj Content-Type: multipart/mixed; boundary="D2o1fIkniFuo7qM01ZekkWlhSq1xQYKyK"; protected-headers="v1" From: Thomas Zimmermann To: stsp , linux-fbdev@vger.kernel.org, Linux kernel Message-ID: Subject: Re: drmfb console switching problems/questions References: <17980f58-c2d2-ac58-88ce-e21b5a56da39@yandex.ru> <70ce31ca-5922-584c-8631-3853c488f3c7@yandex.ru> In-Reply-To: <70ce31ca-5922-584c-8631-3853c488f3c7@yandex.ru> --D2o1fIkniFuo7qM01ZekkWlhSq1xQYKyK Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hi Am 09.10.20 um 14:16 schrieb stsp: > 09.10.2020 14:59, Thomas Zimmermann =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> Fbdev exposes the video ram (or a shadow buffer of it) to all >> applications. Only one can draw at the same time. It's a limitation of= >> the design. To fix this, your application has to stop drawing when you= >> switch consoles. > OK, thanks for info. > Quite a sad news, if you ask me. > Is there any ongoing work at solving that? I don't think so. Both, SDL1 and fbdev, are pretty much dead these days. The solution to fbdev is DRM, which does not have these problems. You could your application under X11 to use SDL's X backend. X would do all the VC handling then. For SDL advice you should ask on the SDL mailing list. >=20 > Anyway, the fact that fb can > permanently hang, is, I suppose, > another problem - the one that > can't be worked around in an app. > I suspect it is the result of sdl doing > ioctl(console_fd, KDSETMODE, KD_GRAPHICS); > After which, I think, redrawing on a > VC switch became disabled. > Would it make sense to improve SAK > to unfreeze from that? Otherwise its > too easy to hang the screen permanently, > and no way to recover. That 'hung-up' problem you described sounds like the fbdev console does not correctly redraw itself. But I don't know where the related code is located. Best regards Thomas --=20 Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany (HRB 36809, AG N=C3=BCrnberg) Gesch=C3=A4ftsf=C3=BChrer: Felix Imend=C3=B6rffer --D2o1fIkniFuo7qM01ZekkWlhSq1xQYKyK-- --M5HWfsROMBtVeEnVUOr9Di9KQ5NWpqinj Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQFIBAEBCAAyFiEEchf7rIzpz2NEoWjlaA3BHVMLeiMFAl+AXpMUHHR6aW1tZXJt YW5uQHN1c2UuZGUACgkQaA3BHVMLeiNWdAf/Y5A3n2fl8B4PiBhTsI2gOaA4SHmk ld8C+gKmkAdTLXSDXXqvIuGFLYow4Q4wDpJI1VMsj2d5fWWcfSBGv/QOMFnsduBt rDVRFn8XTiFmAErCrhbUC1wlGQRLThWzmPft8vKUVtWm2EyP/nL6fF8qT9V13vm0 yhVqSqH7zrI0T7bDOUkPNsHeDvKp/aHrRmi2cU1paYTWuY95S8vUNU3J52kdcpLy 76rFzTBOIgB0vBtyMnVa/L3s+99D/xPHJbUe7NzjIwDSBOsXMgYYc+qRSLCaB0TS zQwGXUAzxX/s2Q8akUsAw9vyR/BxIageZWpQ+oVLZFhHnssEFi2iaWelLQ== =7cbK -----END PGP SIGNATURE----- --M5HWfsROMBtVeEnVUOr9Di9KQ5NWpqinj--