On Sep 23, 2015, at 3:25 PM, Edward Tomasz Napierała <tr...@freebsd.org> wrote:

> On 0923T0916, John Nielsen wrote:
>> On Sep 23, 2015, at 2:12 AM, Yonas Yanfa <yo...@fizk.net> wrote:
>>> isboot is a iSCSI boot driver written by Daisuke Aoyama that allows you to 
>>> boot your root partition using iSCSI.
>> [,,,]
>>> This was first announced way back in June, 2010:
>>> https://lists.freebsd.org/pipermail/freebsd-scsi/2010-June/004425.html
>>> I've tested the current version (v0.2.10) and it works with FreeBSD 10.2 
>>> booting a ZFS on root installation:
>>> http://www.peach.ne.jp/archives/isboot/isboot-0.2.10.tar.gz
>>> I've used iSCSI boot with Ubuntu Server for a while and it's been very 
>>> useful. I'm looking forward to FreeBSD having the same capability built-in.
>> +1. I have used this module in the past and it is extremely useful. Thanks 
>> for the pointer, I wasn’t aware it had been updated for FreeBSD 10.x so 
>> recently. I’ve also wondered why this is not part of FreeBSD by default.
>> Aoyama-san, do you have any objection to this code being included in 
>> FreeBSD? If not, can you formally assign it a BSD or other friendly license? 
>> Thank you again for the work!
>> Trasz (or anyone), is there other work to support iSCSI booting and/or IBFT 
>> on FreeBSD? Anything else isboot might conflict with? Any problems with 
>> integrating the code or with the code itself?
> The basic problem with isboot is that it only works with the old iSCSI
> initiator, which is now marked obsolete.  AFAIK there is no ready solution
> that works with the new one - however, it should be possible to use upcoming
> reroot support to achieve this: boot with a temporary rootfs, mounted from
> a ramdisk preloaded by loader(8), setup an iSCSI session, and then replace
> the temporary rootfs with the real one, mounted over iSCSI.

Ah, thank you for clarifying. I forgot that 10.x still supports the old 

The reroot approach sounds interesting but less straightforward. The beauty of 
isboot is that the kernel—loaded from a normal root disk that happens to be 
iSCSI-connected—knows how to re-establish its network and iSCSI connections 
just from the information in the iSCSI Boot Firmware Table, i.e. native iSCSI 
booting. I’d love to see the same approach continued with the new initiator. I 
suspect that a new implementation could re-use all of the IBFT code and most of 
the networking code, but I don’t know how hard the remaining pieces would be. I 
may have a chance to look in to it but a kernel programmer I am not, sadly.

I think a “native” iSCSI reroot approach could be feasible at some point; for 
me that would mean that the loader could load the kernel and a standard-ish (or 
easily auto-generated) mfsroot from the iSCSI volume seamlessly, then something 
in the mfsroot parses the IBFT and sets up the network and iSCSI connections 
before switching root.


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