From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linutronix.de (193.142.43.55:993) by crypto-ml.lab.linutronix.de with IMAP4-SSL for ; 14 Oct 2019 19:51:53 -0000 Received: from mx2.suse.de ([195.135.220.15] helo=mx1.suse.de) by Galois.linutronix.de with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iK6Nj-0006Jy-Uy for speck@linutronix.de; Mon, 14 Oct 2019 21:51:53 +0200 Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 19EA8B529 for ; Mon, 14 Oct 2019 19:51:45 +0000 (UTC) Date: Mon, 14 Oct 2019 21:51:42 +0200 (CEST) From: Jiri Kosina Subject: [MODERATED] Re: [PATCH v5 08/11] TAAv5 8 In-Reply-To: Message-ID: References: <20191009131251.GD6616@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit To: speck@linutronix.de List-ID: On Mon, 14 Oct 2019, speck for Thomas Gleixner wrote: > The real question is whether machines on which SAP/HANA runs are just > random boxes/VMs which would be affected by the 'update and reboot > world' treatment or whether SAP/HANA runs on dedicated systems which are > carefully administrated by sysadmins with brains turned on. > > If it's the random box affected by 'update and reboot world' then disabling > TSX by default is obviously going to be a source of regressions and we have > to bite the bullet. > > If not, then the sysadmins will anyway do some very careful evaluation > and checking, read documentation and add 'WE_REALLY_WANT_TSX' on the > kernel command line. In that case I rather disgruntle a few sysadmins > and gain a useful setup for everyone else. [ if this archive is ever going to be published, please remove this mail from it, thanks ] So we talked to SAP about exactly this, and they expressed a real worry along the lines of (just my paraphrase, not really verbatim quote of anybody): "of course we will put it into a SAP note (*), but realistically, not everybody (by far) is reading those. If this regressess on a handful of platforms, we (together with the OS vendor) could probably handle the followup reports, but if it happens all across the board, it'd surely be overwhelming, to put it mildly. It'll" basically promptly escalate to a support disaster." (*) kind of a release/technical notes, an accompanying documentation for update/release, where they can indicate the need of kernel commandline parameter to be added Thanks, -- Jiri Kosina SUSE Labs