From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: Regression - SATA disks behind USB ones on v4.8-rc1, breaking boot. [Re: Who reordered my disks (probably v4.8-rc1 problem)] Date: Sun, 14 Aug 2016 16:15:44 +0200 Message-ID: <20160814141544.GA2351@kroah.com> References: <20160813190340.GA29989@amd> <20160814092044.GA20392@amd> <20160814100102.GA31847@amd> <20160814112958.GA20778@kroah.com> <20160814120327.GA8292@amd> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20160814120327.GA8292@amd> Sender: linux-kernel-owner@vger.kernel.org To: Pavel Machek Cc: David Lang , Tom Yan , kernel list , james harvey , regressions@leemhuis.info, hdegoede@redhat.com, Tejun Heo , linux-ide@vger.kernel.org, linux-usb@vger.kernel.org, Oliver Neukum , Alan Stern List-Id: linux-ide@vger.kernel.org On Sun, Aug 14, 2016 at 02:03:27PM +0200, Pavel Machek wrote: > Hi! > > > > > > I have no idea how "SATA before USB" had been done in the past (if it > > > > > was ever a thing in the kernel), but that has not been the case since > > > > > at least v3.0 AFAIR. > > > > > > > > > > > > > > > > > People may not run udev, and you can't use /dev/disk/by-id on kernel > > > > > > command line. > > > > > > > > > > > > > > > > No, but you can always use root=PARTUUID=, that's built into the > > > > > kernel. (root=UUID= requires udev or so though). > > > > > > > > Silly me. root=UUID= has nothing to do with udev, but `blkid` in > > > > util-linux. At least that's how it's done in Arch/mkinitcpio. > > > > > > The rule is "don't break working systems", not "but we are allowed to break > > > systems, see it says here not to depend on this" > > > > > > Drive ordering has been stable since the 0.1 kernel [1] > > > > Drive probing order of USB has always been non-deterministic, so while I > > agree that it is not good to break existing systems at all, perhaps this > > is on the edge of what works vs. doesn't work? > > Yeah, USB order is known to be random. But root=/dev/sda (when sda is > on SATA) is very old, and it would be good to keep it. > > > I know my USB drives always seem to come up in random order, which is > > why tools like udev were invented :) > > > > > It takes a lot longer to detect USB drives, why in the world would they be > > > detected before hard-wired drives? > > > > Depends, some hard-wired drives take much longer to find than USB ones. > > > > That being said, it would be great if the original reporter could use > > 'git bisect' and let the linux-usb and linux-scsi mailing list know what > > the offending patch is, and we can take it from there. > > Original reporter is me :-(. > > Yes, I can do bisect, if required. I'd like some kind of confirmation > that it happens on other systems... Please use git-bisect, you are the first one reporting this. thanks, greg k-h