[CentOS] Upgrading (?) from legacy boot to UEFI

Mon Aug 30 14:37:15 UTC 2021
Jon Pruente <jpruente at riskanalytics.com>

On Sat, Aug 28, 2021 at 8:47 AM Valeri Galtsev <galtsev at kicp.uchicago.edu>

> On August 28, 2021 8:07:30 AM CDT, Jonathan Billings <billings at negate.org>
> wrote:
> >On Aug 28, 2021, at 05:58, Rob Kampen <rkampen at kampensonline.com> wrote:
> >>
> >> As to the RH decision to default to a legacy boot / MBR oriented
> install based upon size of disk ... words fail me.
> >
> >I don’t think that it chooses legacy boot based on the size of disk, but
> based on how you booted the installer.  If you booted from the installer as
> a legacy boot item, it installs as a legacy bootloader, but if you disable
> the BIOS option to use a legacy bootloader, it will boot the installer as a
> UEFI boot and choose to install a UEFI grub2 setup.
> >
> +1
> And the same seems to be true about other UNIX like systems, at least
> Debian and clones, FreeBSD and clones.

This has been my experience as well. If the installer is booted in legacy
mode then it will install as it needs to for a BIOS system. If it is booted
in UEFI mode then it will install as needed for a UEFI boot. Trying to boot
in legacy mode and install for UEFI boot is fraught with a lot of manual
complications. IMO it's not any more complicated than understanding the
limits of legacy BIOS booting and all the workarounds that have been
stacked up over the decades to keep it working.