From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga03.intel.com ([143.182.124.21]) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1SwySM-00058d-BE for linux-mtd@lists.infradead.org; Thu, 02 Aug 2012 16:41:02 +0000 Message-ID: <1343925930.25013.163.camel@sauron.fi.intel.com> Subject: Re: UBI fastmap updates From: Artem Bityutskiy To: Richard Weinberger Date: Thu, 02 Aug 2012 19:45:30 +0300 In-Reply-To: <20120802183210.7076aa48@spider.haslach.nod.at> References: <1341836323-43916-1-git-send-email-richard@nod.at> <1343916747.25013.112.camel@sauron.fi.intel.com> <20120802161512.5ac7a303@spider.haslach.nod.at> <1343917741.25013.114.camel@sauron.fi.intel.com> <20120802165132.1bf1e5d7@spider.haslach.nod.at> <1343924267.25013.156.camel@sauron.fi.intel.com> <20120802183210.7076aa48@spider.haslach.nod.at> Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-IhLBQdzXFe/FmfaN8Tue" Mime-Version: 1.0 Cc: nyoushchenko@mvista.com, linux-kernel@vger.kernel.org, adrian.hunter@intel.com, Heinz.Egger@linutronix.de, thomas.wucher@linutronix.de, linux-mtd@lists.infradead.org, shmulik.ladkani@gmail.com, tglx@linutronix.de, Marius.Mazarel@ugal.ro, tim.bird@am.sony.com Reply-To: artem.bityutskiy@linux.intel.com List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-IhLBQdzXFe/FmfaN8Tue Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Richard, On Thu, 2012-08-02 at 18:32 +0200, Richard Weinberger wrote: > > This should not happen. Fastmap should _reserve_ enough of PEBs for it > > to operate. It should always find the PEB to write. >=20 > What is the benefit? > IOW what is wrong with the current approach? Several reasons. The main is: fastmap will start consuming PEBs reserved for volumes when the amount of available PEBs is just enough to map all LEBs. This will break UBI liability. > Why? > If everything goes wrong, fastmap makes sure that no fastmap is on > flash. > In case of a powercut we fall back to scanning mode. > R/O mode is overkill IMHO. So can I interpret this the following way. Not only fastmap give no guarantees that it exists after an unclean reboot, it does not even give guarantees that it exists after a clean reboot. Unless I am confused, the fastmap design is over-simplified. --=20 Best Regards, Artem Bityutskiy --=-IhLBQdzXFe/FmfaN8Tue Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAABAgAGBQJQGq6qAAoJECmIfjd9wqK0w5sP/R0Lhh2KGl2j6ictpIiDn4pU lxLBsBEyUYmKGEX0etKFPI/e431PzU+ifzRQUH2OTUz7SiCFjjr6u7YSp3feczY2 FmVomzLXH1L4R5xEJyCc6zhuUiIe9BpLCJqNJkkiA++ufjdvv44RCsMjItwgRLQj XTgjiAH2snOYwnNgMdmbbtkzynMuKvZmFp/BR2gXfyIVcwXqpw6T6zeH7AzTAbf8 uqTxuHXpCuLIo0f2wNvUBFe3fDo5l/+sRjF4mKWYl26E+QuUfLw/JuPW/oULP0rT H1dVH9d98FEEkDTTW5R2Ea/hz9aORhIdXjOefyP6hrW+C7je4NeplG6Pu2IY39KG MUNt0U8ERmJQ7BpxG8Zj0KxteylHNI1ZJwmqvacXVTxMOzqROzNphAqn7bwFAq7l xdyBOj/g6opIxxLxArUwt1e8I41rrLhM5Wj4kA6uNQnsHgHibbRTOwykTzypna1k AQv8bC44BbMBEOVFDiti6un/o9ub9AUav698JpC/rbwm6W7+cKu3BYXAklB0k2t6 60kzOTwtL7KI3Dg/wyyUGef24AElNigF70NVfPLxHa0CW5zbMcblHNod1WUSyX4i PxW67tCUC+HTe3Drv2svPpT5QpVI+oZD10xzzRZHLC7xtNl8hJQTWl+dp1ocBIcD vRFa/Ehk+BmirkKuCja2 =rhGe -----END PGP SIGNATURE----- --=-IhLBQdzXFe/FmfaN8Tue--