The other problem : AHCI unbootable

Warren Block wblock at
Sat Jun 25 12:24:00 UTC 2016

On Sat, 25 Jun 2016, Dave wrote:

> On Saturday 25 June 2016 04:56:39 Manish Jain wrote:
>> While installing FreeBSD 10.3 amd64, I tried switching from IDE to AHCI
>> in my BIOS's boot configuration. But when I do this, the installer
>> installs the OS on the hard disk, and then the system is unbootable -
>> the BIOS screen hangs with the message : boot record missing.
>> Can anyone please tell me what might be the problem ?
> Not sure exactly what you are saying your process is, but switching between AHCI and IDE without a full and clean install will cause you problems.  Solution.  Don't do it.

This has not been a problem for me with FreeBSD.  The drivers and 
operating system are resilient enough to detect which mode is available 
and just use it.  AHCI is preferred, though, giving a roughly 5-15% 
speed improvement.

> This advice applies at least to WinXP too.  That tends to reboot while 
> the Windows logo is on screen no matter which way around you do it. ie 
> if you install in IDE mode it will reboot if change to AHCI mode. 
> Same happens if you install in AHCI mode and then try to boot in IDE 
> mode.

I can't recall about XP, but later versions do have AHCI drivers 
available.  If the machine is to be dual-booted, that will limit the 
modes available to what works with the most limited operating system. 
Using FreeBSD as a single operating system and running the others as VMs 
with VirtualBox is one way around this.

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