Date: Tue, 14 Jun 2016 10:15:41 -0600 From: Ian Lepore <ian@freebsd.org> To: Russell Haley <russ.haley@gmail.com> Cc: freebsd-arm <freebsd-arm@freebsd.org>, Lou Katz <pi@metron.com> Subject: Re: A possible solution to booting from another USB stick Message-ID: <1465920941.1188.150.camel@freebsd.org> In-Reply-To: <CABx9NuRPcdebfae88yQJsgfF0mnnYBBOXeGrtT8nynmhUhut4g@mail.gmail.com> References: <20160610071928.GA75585@metron.com> <1465864289.1188.140.camel@freebsd.org> <CABx9NuRPcdebfae88yQJsgfF0mnnYBBOXeGrtT8nynmhUhut4g@mail.gmail.com>
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On Tue, 2016-06-14 at 08:46 -0700, Russell Haley wrote: > On Mon, Jun 13, 2016 at 5:31 PM, Ian Lepore <ian@freebsd.org> wrote: > > On Fri, 2016-06-10 at 00:19 -0700, Lou Katz wrote: > > > It occurred to me that as long as I had the same version of > > > FreeBSD > > > on the > > > bootable card and in a USB adapter I could boot normally, then > > > mount > > > the system on the adapter card and do a chroot. > > > > > > A quicky and dirty test indicates that might work for what I want > > > to > > > do, > > > which is to: > > > a. modify an application > > > b. add or subtract data files > > > and as a freebie, I seem to get > > > c. ability to change things without rebooting. > > > > > > I will report back after I try this in earnest. > > > > > > Thanks for the feedback. > > > > > > > I apparently missed the first round of this question. > > > > In uboot, you need to do a "usb start", then do "usb dev" and see > > if it > > recognizes your disk device. If so, you're in business, tell ubldr > > to > > load the kernel from it instead of sdcard by doing: > > > > setenv loaderdev disk1 > > > > If there are multiple disks you might need disk2, disk3, whatever. > > If > > there are multiple partitions involved you might need, for example, > > disk1:2 to boot from partition 2. > > So does that mean there are three possible answers? > > 1) Create a new kernel and set ROOTDEVNAME" > > options ROOTDEVNAME=\"ufs:mmcsd0s2\" > The ROOTDEVNAME from kernel config is used as a fallback if no vfs.root.mountfrom is set. It's generally useful only when you bypass ubldr and load the kernel directly from uboot. > > 2) If you have a good image with a kernel and rootfs on USB use a > u-boot environment variable: > > uboot> setenv loaderdev disk1 > This is the way to get the kernel and the root filesystem to come from the same alternate disk device/partition. > > 3) If you can set the loader.conf file and want to run kernel on a > default image (sdcard) and rootfs on USB: > > /boot/loader.conf > > (on the sd-card root) has > > vfs.root.mountfrom="ufs:/dev/ufs/bsd11" If you have this in loader.conf, it will override ubldr's logic that automatically sets it from what it finds in /etc/fstab. You'd get the effect of the kernel coming from sdcard, and the rootfs from another device. -- Ian
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