BSDInstall: merging to HEAD

James R. Van Artsdalen james-freebsd-current at
Fri Jan 21 06:00:06 UTC 2011

On 1/20/2011 3:37 PM, David Demelier wrote:
> Why does the installer use GPT partition by default? Do you know that
> GPT is not supported on every (even modern) computer ?

GPT is fully compatible with the universe of PC/AT BIOS-compatible
computers, which is essentially all "PCs" going back to the IBM model
5170 released in 1984.

GPT contains a valid boot sector which is sufficient for a
PC/AT-compatible to boot the OS.  There's also a valid MBR should anyone
look for that.

There have been reports of computers with buggy BIOSs that fail with
GPT.  It's not clear how to make them work since they're failing with a
*valid* MBR, i.e., the failure indicates they fail with some correct
MBRs and we can't be sure they'll work even if we write an MBR instead
of GPT.

PS. In a previous life I did PCs.  Every system I released after 1988 or
so would work with GPT.  It's hard to get this one wrong and still be

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