MFC r334310, r334337:
r334310 (imp):
Teach ufs_module.c about bsd labels and probe 'a' partition. If the check for a UFS partition at offset 0 on the disk fails, check to see if there's a BSD disklabel at block 1 (standard) or at offset 512 (install images assume 512 sector size). If found, probe for UFS on the 'a' partition. This fixes UEFI booting images from a BSD labeled MBR slice when the 'a' partiton isn't at offset 0. This is a stop-gap fix since we plan on removing boot1.efi in FreeBSD 12. We can't easily do that for 11.2, however, hence the short MFC window.
r334337 (emaste):
switch amd64 memstick installer images to MBR A good number of BIOSes have trouble booting from GPT in non-UEFI mode. With this change amd64 memsticks remain dual-mode (booting from either UEFI or CSM); the partitioning type is just switched from GPT to MBR.
PR: 227954
Note, there are two changes specific to stable/11 where there is code
that had diverged from head and never merged back. The two changes are
an include in stand/efi/boot1/ufs_module.c, replacing sys/disk/bsd.h
with sys/disklabel.h and replacing BSD_MAGIC with DISKMAGIC in the
same file. The latter two are direct commits to stable/11 in order to
avoid unexpected regressions at this point of the 11.2 cycle. Thank
you to imp@ for pointing out what changes needed to be made.
Approved by: re (marius)
Sponsored by: The FreeBSD Foundation