On 1/19/2019 10:32, Rodney W. Grimes wrote: >> ...... > The BIOS does NOT do what our boot0 does, I have seen no BIOS that > well allow me to select a partition on a drive, you can only select > the drive. > > I think this is the feature that Lev is missing, and I am sure > others shall miss it to. > > IIRC whistle used a version of this so you could install a new system > to partion 2, keeping your current system in partion 1, and changing the > active back and forth. If we have lost that basic functionality with > the growth of GPT and UEFI that is a sad day. It is indeed, especially for embedded applications. I really, really like the fact that NanoBSD (on an MBR boot) can have two partitions and mark the "other one" as active; this then lets you update the code "in place" and as long as you are paying attention to what goes into the volatile overlays (specifically although not exclusively don't let /etc/fstab with a hard-coded filesystem reference get into there!) then you can "warm update" a running system and reboot into the new code. If something goes wrong re-marking the old partition active is not terribly hard, so there's a *reasonable* recovery path available. I've not found a reliable way to do that sort of thing with many of the "newer" small-board devices and I really like it on, for example, my apu2 firewall appliances that I and others are using all over the place in that being able to put together a code-fix update is of material value. -- Karl Denninger karl_at_denninger.net /The Market Ticker/
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