* include/grub/util/getroot.h (grub_dev_abstraction_types): New enum.
(grub_util_get_dev_abstraction): New function prototype.
* util/getroot.c: Include `<grub/util/getroot.h>'
(grub_util_get_grub_dev): Move detection of abstraction type to ...
(grub_util_get_dev_abstraction): ... here (new function).
* util/grub-probe.c: Convert PRINT_* to an enum. Add
`PRINT_ABSTRACTION'.
(probe): Probe for abstraction type when requested.
(main): Understand `--target=abstraction'.
* util/i386/efi/grub-install.in: Add abstraction module to core
image when it is found to be necessary.
* util/i386/pc/grub-install.in: Likewise.
* util/powerpc/ieee1275/grub-install.in: Likewise.
* util/update-grub_lib.in (font_path): Return system path without
converting to GRUB path.
* util/update-grub.in: Convert system path returned by font_path()
to a GRUB path. Use `grub-probe -t abstraction' to determine what
abstraction module is needed for loading fonts (if any). Export
that as `GRUB_PRELOAD_MODULES'.
* util/grub.d/00_header.in: Process `GRUB_PRELOAD_MODULES' (print
insmod commands).
All executable files in this directory are processed in shell expansion order. 00_*: Reserved for 00_header. 10_*: Native boot entries. 20_*: Third party apps (e.g. memtest86+). The number namespace in-between is configurable by system installer and/or administrator. For example, you can add an entry to boot another OS as 01_otheros, 11_otheros, etc, depending on the position you want it to occupy in the menu; and then adjust the default setting via /etc/default/grub.