Speaking of UEFI

Chris Murphy lists at colorremedies.com
Mon Dec 9 17:00:13 UTC 2013

On Dec 9, 2013, at 7:48 AM, Mark Haney <mhaney at practichem.com> wrote:

> This might be slightly off-topic, but here's the problem, I'm having a
> devil of a time getting my daughter's laptops to downgrade to Win7
> with UEFI enabled.  F19 installed beautifully, but Win7 has become a
> real PITA.
> So, let's assume what I want to do is switch from UEFI to BIOS booting
> to get Win7 installed.  How possible would it be to repair the
> existing F19 install to boot via the same method?  Would I have to
> just wipe it and re-install?

Windows 7 BIOS requires an MBR partitioned disk. So you'll need to change the partition scheme from GPT to MBR before you can install Windows 7. After installing Windows 7, you can boot DVD or netinst media in rescue mode, chroot the mounted system at /mnt/sysimage and then:

grub2-install /dev/sda
grub2-mkconfig -o /boot/grub2/grub.cfg

The bigger issue, which requires testing, is how the CSM-BIOS is going to behave with either Windows 7 or Fedora in particular power management and peformance. My two EFI laptops are Macs and when booted in CSM mode, SATA disks become IDE, and ACPI isn't fully enabled, and I don't get very good battery life or performance as a result. This isn't universal, you'd have to test it. But you have to understand that the CSM real BIOS to the operating system. The intent is to support legacy OS's, not necessarily to do this with the best performance the hardware has to offer. That's what the native firmware setting should do.

I'm sufficiently experienced with multibooting that I think it's basically a crap UX, that becomes 1000x worse than crap if anything goes wrong, which forums indicate is a decent probability. So I'd pick one, and VM the other, honestly.

Chris Murphy

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