Date: Wed, 1 Jan 2020 16:39:02 +0100 From: Polytropon <freebsd@edvax.de> To: "Thomas Mueller" <mueller6722@twc.com> Cc: freebsd-questions@freebsd.org Subject: Re: Need help trying to recompile kernel with EBR functionality Message-ID: <20200101163902.60776151.freebsd@edvax.de> In-Reply-To: <202001011526.001FQUeA001903@r56.edvax.de> References: <DB8PR06MB6442B425832B28E6E16AC181F6210@DB8PR06MB6442.eurprd06.prod.outlook.com> <202001011526.001FQUeA001903@r56.edvax.de>
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On Wed, 01 Jan 2020 06:19:33 +0000, Thomas Mueller wrote: > > I am a long time user of FreeBSD but have never recompiled my kernel. > > > > I am trying to compile a custom 12.1 amd64 kernel with the ability > > to add/delete EBR partitions, but the online documentation did not > > help and I ended up losing EBR functionality entirely. > > > > The steps I followed were as under : > > > > 1) copied [/usr/src/sys/amd64/conf/]GENERIC as EBRKERNEL > > > 2) commented out GEOM_PART_EBR_COMPAT in [/usr/src/sys/amd64/conf/]DEFAULTS A little sidenote: Do not change that file. All your kernel configurations should be in the kernel configuration file. In order to deviate from the defaults, use "nooption <name>" to disable an existing option, and (as shown correctly) "option <name>" to add an additional one; same for "device" and "nodevice". > > 3) inserted 'options GEOM_PART_EBR' into my kernel configuration > > file EBRKERNEL > > > 4) cd /usr/src > > > 5) make buildkernel KERNCONF=EBRKERNEL > > > 6) make installkernel KERNCONF=EBRKERNEL > > > > When I shutdown the system and rebooted into the new kernel, the > > boot process halted complaining that it could find any device > > /dev/ada0s5 (the EBR partition). > > > > What am I doing wrong ? Any help in getting me a good custom kernel > > with the ability to add/delete EBR partitions would be greatly appreciated. > > > Thank you & Regards, > > Manish Jain > > I am rather confused here. My first inclination would be to suggest > you switch to GPT. This often is not an option for multi-OS settings because it lacks boot selection (through FreeBSD's boot manager), and the support across different operating systems (for example, read partition of of OS 1 from OS 2) sometimes causes trouble when GPT is involved. > Using MBR, you get up to 4 partitions, of which one may be > an extended boot record. That partition is a container for > logical-partition data, not a partition that can be mounted > or copied to or from. The "DOS extended partition" (which contains "logical volumes") is not to be addressed directly; instead the "logical volumes" inside it are. And that's completely okay for non-bootable partitions (such as data partitions). So basically there are 3 "DOS primary partitions" (bootable - 3 systems), one "slot" for the "DOS extended partition", and inside it, any further partitions needed, for example shared /home partitions for Linux. FreeBSD itself does not need any of this. ;-) > It seems to me the EBR partition would be s1, s2, s3, or s4 > but no higher. I'd need to see your full partition table > data, such as you get with "fdisk -lu" in Linux, or you can > use gpart with "show" in FreeBSD. If I remember the numbering system correctly, s1 - s4 are reserved for "DOS primary partitions" - slices. The "logical volumes" as well as the "DOS extended partition" containing them have a higher "s value". > Maybe you have the wrong partition name (ada0s5)? You can > go to the loader prompt and get a rough idea of what's in > the partitions, and change the root partition to boot into. So if ada0s5 is the "DOS extended partition", it's absolutely understandable that no partition (read: slice) can be found. I think the problem here is that the number is wrong. It's worth verifying the correct numbers with gpart. The "logical volumes" that need to be addressed (as a "slice equivalent") then probably should be ada0s6 and so on. > I have created logical partitions with Linux fdisk but never > any BSD fdisk. I believe there is a linuxfdisk in FreeBSD > ports, category would be sysutils to the best of my memory. In the past, I used FreeBSD's ye olde fdisk for partition creation, it worked, but the common suggestion was to use the OS that would be _using_ the partition for initializing it, and adding the required file systems. WIth goart, however, this should basically work. -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...
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