FreeBSD slices and the Boot Manager

Warren Block wblock at
Sun Jul 28 21:59:37 UTC 2013

On Sun, 28 Jul 2013, Conny Andersson wrote:

> Hi Warren and Polytropon,
> A few minutes ago I booted up from a FreeBSD-8.4-RELEASE-amd64-memstick.img 
> to experience that it is sysinstall that is used in that release.
> Next, I did a 'dummy' custom installation. And, as I supposed sysinstall 
> recognized disk ada0 as ad4 and disk ada1 as ad6. Then I aborted sysinstall 
> and rebooted in to my FreeBSD 8.3-Release.
> Well, AHCI (Serial ATA Advanced Host Controller Interface driver) seems 
> involved when identifying disks and slices. But, only on newer computers who 
> has this option set to on in the BIOS. Maybe, bsdinstall in FreeBSD 9.0 and 
> onwards can make use of AHCI directly.

At some point, the old ad(4) driver was replaced with the new ada(4) 
driver.  To provide backwards compatability, the old ad devices names 
are still available in /dev.  I don't know when FreeBSD 8.X switched to 
the ada(4) driver.

Neither ad nor ada devices require AHCI.  If it is available, it gives a 
small but noticeable speed increase.  Otherwise, it should make no 

> More apropos labels: The latest BIOS version 2.4.0 for Dell T1500 does not 
> support UEFI/GPT/GUID. As far as I know, Dell only have the Unified 
> Extensible Firmware Interface on its PowerEdge servers.

There is more than one kind of label.  There are filesystem labels 
like we are talking about, there are GPT labels, there are generic 
labels.  The ones being suggested are filesystem labels:

FreeBSD supports GPT without UEFI.  It doesn't matter in this case, 
since you already have MBR.

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