Implementation of the do_bootm_linux() and other bootm helper routines is
architecture specific code. As such it resides in lib_<arch> directories
in files named <arch>_linux.c
This patch renames those files to a more clear and accurate
lib_<arch>/bootm.c form.
List of the renamed files:
lib_arm/armlinux.c -> lib_arm/bootm.c
lib_avr32/avr32_linux.c -> lib_avr32/bootm.c
lib_blackfin/bf533_linux.c -> lib_blackfin/bootm.c
lib_i386/i386_linux.c -> lib_i386/bootm.c
lib_m68k/m68k_linux.c -> lib_m68k/bootm.c
lib_microblaze/microblaze_linux.c -> lib_microblaze/bootm.c
lib_mips/mips_linux.c -> lib_mips/bootm.c
lib_nios/nios_linux.c -> lib_nios/bootm.c
lib_nios2/nios_linux.c -> lib_nios2/bootm.c
lib_ppc/ppc_linux.c -> lib_ppc/bootm.c
lib_sh/sh_linux.c -> lib_sh/bootm.c
Signed-off-by: Marian Balakowicz <m8@semihalf.com>
Check for overwrites during image move/uncompress, return with error
when the original image gets corrupted. Report clear message to the user
and prevent further troubles when pointer to the corrupted images is passed
to do_bootm_linux routine.
Signed-off-by: Marian Balakowicz <m8@semihalf.com>
- use single image header pointer instead of a set of auxilliary variables.
- add multi component image helper routines: get component size/data address
Signed-off-by: Marian Balakowicz <m8@semihalf.com>
CHUNKSZ defined for PPC and M68K is set to the same value of 64K,
move this definition to a common header.
Signed-off-by: Marian Balakowicz <m8@semihalf.com>
Make CONFIG_OF_LIBFDT and CONFIG_OF_FLAT_TREE use more
readable in PPC variant of do_bootm_linux() routine.
Signed-off-by: Marian Balakowicz <m8@semihalf.com>
- Fix EEPROM_data structure definition according to System EEPROM Data Format.
- Read MAC addresses from EEPROM to ethXaddr before saving ethXaddr to
bd->bi_ethaddr.
Signed-off-by: Haiying Wang <Haiying.Wang@freescale.com>
This patch adds support for the SPI controller found on Freescale PowerPC
processors such as the MCP834x family. Additionally, a new config option,
CONFIG_HARD_SPI, is added for general purpose SPI controller use.
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
This is an API for external (standalone) applications running on top of
U-Boot, and is meant to be more extensible and robust than the existing
jumptable mechanism. It is similar to UNIX syscall approach. See api/README
for more details.
Included is the demo application using this new framework (api_examples).
Please note this is still an experimental feature, and is turned off by
default.
Signed-off-by: Rafal Jaworowski <raj@semihalf.com>
platforms wishing to display RAM diagnostics in addition to size,
can do so, on one line, in their own board_add_ram_info()
implementation.
this consequently eliminates CONFIG_ADD_RAM_INFO.
Thanks to Stefan for the hint.
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
83xx processor family has many reset sources, such as
power on reset, software hard reset, software soft reset,
JTAG, bus monitor, software watchdog, check stop reset,
external hard reset, external software reset.
sometimes, to figure out the fault of system, we need to
know the cause of reset early before the prompt of
u-boot present.
Signed-off-by: Dave Liu <daveliu@freescale.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
During config transactions on the PCIe bus an attempt to scan for a
non-existent device can lead to a machine check exception with certain
peripheral devices. In order to avoid crashing in such scenarios the
instrumented versions of the config cycle read routines are introduced, so
the exceptions fixups framework can gracefully recover.
Signed-off-by: Grzegorz Bernacki <gjb@semihalf.com>
Acked-by: Rafal Jaworowski <raj@semihalf.com>
The relocation fixup didn't handle the malloc pointer initialization
correctly. This patch fixes this problem. Tested successfully on 4xx.
The relocation fixup patches for 4xx will follow soon.
Signed-off-by: Stefan Roese <sr@denx.de>
Fixed some broken instances of "#ifdef CMD_CFG_IDE" too.
Those always evaluated TRUE, and thus were always compiled
even when IDE really wasn't defined/wanted.
Signed-off-by: Jon Loeliger <jdl@freescale.com>
This is a compatibility step that allows both the older form
and the new form to co-exist for a while until the older can
be removed entirely.
All transformations are of the form:
Before:
#if (CONFIG_COMMANDS & CFG_CMD_AUTOSCRIPT)
After:
#if (CONFIG_COMMANDS & CFG_CMD_AUTOSCRIPT) || defined(CONFIG_CMD_AUTOSCRIPT)
Signed-off-by: Jon Loeliger <jdl@freescale.com>
- Show on the Status LEDs, some States of the board.
- Get the MAC addresses from the EEProm
- use PREBOOT
- use the CF on the board.
- check the U-Boot image in the Flash with a SHA1
checksum.
- use dynamic TLB entries generation for the SDRAM
Signed-off-by: Heiko Schocher <hs@denx.de>
Search the exception table with linear algorithm instead of
bisecting algorithm.
Because the exception table might be unsorted.
Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
Conflicts:
drivers/cfi_flash.c
The patch by Heiko Schocher <hs@pollux.denx.de> on Jan, 19, 2007
fixes cfi_driver bug for mpc7448hpc2 board. The default cfi_driver can support
mpc7448hpc2 board.
The original search_one_table() function code can only processes the search
for the exception occurring in FLASH/ROM, because the exception and fixup
table usually locate in FLASH. If the exception address is also in
FLASH, it will be OK.
If the exception occurs in RAM, after the u-boot relocation, a
relocation offset should be added.
clean up the code in cpu/74xx_7xx/cpu.c
Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
The conflicts due to a new mpc7448 p3m7448 board is in the main tree.
Merge branch 'master' into hpc2
Conflicts:
MAKEALL
cpu/74xx_7xx/cpu.c
cpu/74xx_7xx/cpu_init.c
cpu/74xx_7xx/speed.c
Replace all instances of CFG_IMMRBAR with CFG_IMMR, so that the 83xx
tree matches the other 8xxx trees.
Signed-off-by: Timur Tabi <timur@freescale.com>
1. Add 7447A and 7448 processor support.
2. Add the following flags.
CFG_CONFIG_BUS_CLK : If the 74xx bus frequency can be configured dynamically
(such as by switch on board), this flag should be set.
CFG_EXCEPTION_AFTER_RELOCATE: If an exception occurs after the u-boot
relocates to RAM, this flag should be set.
CFG_SERIAL_HANG_IN_EXCEPTION: If the print out function will cause the
system hang in exception, this flag should be set.
There is a design issue for tsi108/109 pci configure read. When pci scan
the slots, if there is no pci card, the tsi108/9 will cause a machine
check exception for mpc7448 processor.
Signed-off-by: Alexandre Bounine <alexandreb@tundra.com>
Signed-off-by: Roy Zang <tie-fei.zang@freescale.com>
- Add support for PPC440EPx & PPC440GRx
- Add support for PPC440EP(x)/GR(x) NAND controller
in cpu/ppc4xx directory
- Add NAND boot functionality for Sequoia board,
please see doc/README.nand-boot-ppc440 for details
- This Sequoia NAND image doesn't support environment
in NAND for now. This will be added in a short while.
Patch by Stefan Roese, 07 Sep 2006
Modifications are based on the linux kernel approach and
support two use cases:
1) Add O= to the make command line
'make O=/tmp/build all'
2) Set environement variable BUILD_DIR to point to the desired location
'export BUILD_DIR=/tmp/build'
'make'
The second approach can also be used with a MAKEALL script
'export BUILD_DIR=/tmp/build'
'./MAKEALL'
Command line 'O=' setting overrides BUILD_DIR environent variable.
When none of the above methods is used the local build is performed and
the object files are placed in the source directory.
Added code for reading and writing Mac addresses to/from ID EEPROM(0x57).
With attached patch, we can use command "mac/mac read/mac save/"
to read and write EEPROM under u-boot prompt.
U-boot will calculate the checksum of EEPROM while bootup,
if it is right, then u-boot will check whether the mac address
of eTSEC0/1/2/3 is availalbe (non-zero).
If there is mac address availabe in EEPROM, u-boot will use it,
otherewise, u-boot will use the mac address defined in
MPC8641HPCN.h. This matches the requirement to set unique mac address
for each TSEC port.
Signed-off-by: Haiying Wang <haiying.wang@freescale.com>
Signed-off-by: York Sun <yorksun@freescale.com>
- Support for TQM8541/8555 boards added.
- Complete rework of TQM8540/8560 support.
- Common TQM85xx code now supports all current TQM85xx platforms
(TQM8540/8541/8555/8560).
- DDR SDRAM size detection added.
- CAS latency default values can be overwritten by setting "serial#"
to e.g. "ABC0001 casl=25" -> CAS latency 2.5 will be used.
If problems are detected with this non default CAS latency,
the defualt values will be used instead.
- FLASH size detection added.
- Moved FCC ethernet driver initialization behind TSEC driver init
-> TSEC is first device.
Patch by Stefan Roese, 30 Nov 2005
The global data pointer, stored in r29 before relocation to RAM, was
not initialized to a correct value. This happened because the pointer
declaration was done locally in the scope of the board_init_f()
function. What follows is a cite from gcc.info, 5.37, "Variables in
Specified Registers":
...
The compiler's data flow analysis is capable of determining where
the specified registers contain live values, and where they are
available for other uses. Stores into local register variables
may be deleted when they appear to be dead according to dataflow
analysis. References to local register variables may be deleted
or moved or simplified.
...
Moving the global data declaration to global scope solved the
problem.
Second serial port on 440GX now defined as a system device.
Add 'Short Etch' code for Cicada PHY within 440gx_enet.c
Patch by Travis B. Sawyer, 12 Jul 2005
Check return value of malloc in 440gx_enet.c
Patch by Travis B. Sawyer, 18 Jul 2005
- Convert the CPM2 based functionality to use new CONFIG_CPM2
option rather than a myriad of CONFIG_MPC8560-like variants.
Applies to MPC85xx and MPC8260 boards, includes stxgp3 and sbc8560.
Eliminates the CONFIG_MPC8560 option entirely. Distributes the
new CONFIG_CPM2 option to each 8260 board.
* Cleanup confusing use of CONFIG_ETH*ADDR - ust his only to
pre-define a MAC address; use CONFIG_HAS_ETH* to enable support for
additional ethernet addresses.
* Cleanup drivers/i82365.c - avoid duplication of code
* Fix bogus "cannot span across banks" flash error message
* Add support for CompactFlash for the CPC45 Board.
Allow clock setting on MPC866/MPC885 series chips according to
environment variable `cpuclk'
* Patch by Yuli Barcohen, 20 Apr 2004:
Remove unnecessary redefine of CPM_DATAONLY_SIZE for MPC826x
* Patch by Sascha Hauer, 28 Jun:
- add generic support for Motorola i.MX architecture
- add support for mx1ads, mx1fs2 and scb9328 boards
* Patches by Marc Leeman, 23 Jul 2004:
- Add define for the PCI/Memory Buffer Configuration Register
- corrected comments in cpu/mpc824x/cpu_init.c
* Add support for multiple serial interfaces
(for example to allow modem dial-in / dial-out)
Completion of the 8540ADS/8560ADS updates:
Fix some PCI and Rapid I/O memory maps,
Initialize both TSEC 1 and 2,
Initialize SDRAM
Update MAINTAINER for 85xx boards and README.mpc85xxads
Using external watchdog for KUP4 boards in mpc8xx/cpu.c;
load_sernum_ethaddr() for KUP4 boards in lib_ppc/board.c;
various changes to KUP4 board specific files
- Add support for RPC/STx GP3, Motorola 8560 board
- Update 85xx TSEC driver so it searches MII for first available PHY
and uses that one.
- Add functions to support console MII commands.
* Patch by Tolunay Orkun, 07 Apr 2004:
Move initialization of bi_iic_fast[]
from board_init_f() to board_init_r()
* Patch by Yasushi Shoji, 07 Apr 2004:
Cleanup microblaze port
* Patch by Sangmoon Kim, 07 Apr 2004:
Add auto SDRAM module detection for Debris board
- add auto-complete support to the U-Boot CLI
- add support for NETTA and NETPHONE boards; fix NETVIA board
* Patch by Yuli Barcohen, 28 Mar 2004:
- Add support for MPC8272 family including MPC8247/8248/8271/8272
- Add support for MPC8272ADS evaluation board (another flavour of MPC8260ADS)
- Change configuration method for MPC8260ADS family
- Unify video mode handling for Chips & Technologies 69000 Video
chip and Silicon Motion SMI 712/710/810 Video chip
- Add selection of the video output (CRT or LCD) via 'videoout'
environment variable for the Silicon Motion
- README update
* Patch by Pierre Aubert, 18 Mar 2004:
include/common.h typo fix
* Patches by Tolunay Orkun, 17 Mar 2004:
- Add support for bd->bi_iic_fast[] initialization via environment
variable "i2cfast" (CONFIG_I2CFAST)
- Add "i2cfast" u-boot environment variable support for csb272
avoid dereferencing NULL pointer in lib_arm/armlinux.c
* Patch by Stephen Williams, 15 Mar 2004:
Fix CONFIG_SERIAL_SOFTWARE_FIFO documentation
* Patch by Tolunay Orkun, 15 Mar 2004:
Initialize bi_opbfreq to real OPB frequency via get_OPB_freq()
* Patch by Travis Sawyer, 15 Mar 2004:
Update CREDITS & MAINTAINERS files for PPC440GX & Ocotea port
add IDE support for MPC5200
* Patch by Masami Komiya, 26 Feb 2004:
add autoload via NFS
* Patch by Stephen Williams
Use of CONFIG_SERIAL_SOFTWARE_FIFO in board.c consistent with uses
elsewhere in the source.
Add support for the Xilinx ML300 platform
* Patch by Stephan Linz, 17 Feb 2004:
Fix watchdog support for NIOS
* Patch by Josh Fryman, 16 Feb 2004:
Fix byte-swapping for cfi_flash.c for different bus widths
* Patch by Jon Diekema, 14 Jeb 2004:
Remove duplicate "FPGA Support" notes from the README file
- update board/emk tree; use common flash driver
- Corrected tested bits in machine check exception in cpu/mpc5xxx/traps.c
[adapted for other PPC CPUs -- wd]
- Added support for the M48T08 on the EVAL5200 board in rtc/mk48t59.c
* Patch by Jon Diekema, 13 Feb 2004:
Call show_boot_progress() whenever POST "FAILED" is printed.
* Patch by Nishant Kamat, 13 Feb 2004:
Add support for TI OMAP1610 H2 Board
Fixes for cpu/arm926ejs/interrupt.c
(based on Richard Woodruff's patch for arm925, 16 Oct 03)
Fix for a timer bug in OMAP1610 Innovator
Add support for CS0 (ROM)/CS3 (Flash) boot in OMAP1610 Innovator and H2
* Patches by Stephan Linz, 12 Feb 2004:
- add support for NIOS timer with variable period preload counter value
- prepare POST framework support for NIOS targets
* Patch by Denis Peter, 11 Feb 2004:
add POST support for the MIP405 board
Add support for IBM PPC440GX. Multiple EMAC Ethernet devices,
select MDI port based on enabled EMAC device.
Add support for XES Inc <http://www.xes-inc.com> XPedite1000 440GX
base PrPMC board.
see doc/README.MPC866 for details;
implement workaround for "SIU4" and "SIU9" silicon bugs on MPC866;
calculate CPU clock frequency from PLL register values.
* Add support for 128 MB RAM on TQM8xxL/M modules
before we can access it; add delay in case we are faster (with no
CF card inserted)
* Cleanup of some init functions
* Make sure SCC Ethernet is always stopped by the time we boot Linux
to avoid Linux crashes by early packets coming in.
* Accelerate flash accesses on LWMON board by using buffered writes
version of the repository???]
* Patch by Reinhard Meyer, 09 Jan 2004:
- add RTC support for MPC5200 based boards (requires RTC_XTAL)
* Add support for IDE LED on BMS2003 board
(exclusive with status LED!)
* Add support for PS/2 keyboard (used with PS/2 multiplexor on
BMS2003 board)
* Patches by Reinhard Meyer, 4 Jan 2004 + 7 Jan 2004:
Add common files for "emk" boards
* Minor code cleanup (coding style)
* Patch by Reinhard Meyer, 30 Dec 2003:
- cpu/mpc5xxx/fec.c: added CONFIG_PHY_ADDR, added CONFIG_PHY_TYPE,
- added CONFIG_PHY_ADDR to include/configs/IceCube.h,
- turned debug print of PHY registers into a function (called in two places)
- added support for EMK MPC5200 based modules
* Fix MPC8xx PLPRCR_MFD_SHIFT typo
* Add support for TQM866M modules
* Fixes for TQM855M with 4 MB flash (Am29DL163 = _no_ mirror bit flash)
* Fix a few compiler warnings
Move most of the timer interrupt related PPC code to ppc_lib/interrupts.c
* Patch by Anders Larsen, 17 Sep 2003:
Bring ARM memory layout in sync with the documentation:
stack and malloc-heap are now located _below_ the U-Boot code
recent tools
* Add checksum verification to 'imls' command
* Add bd_info fields needed for 4xx Linux I2C driver
* Patch by Martin Krause, 4 Nov. 2003:
Fix error in cmd_vfd.c (TRAB board: "vfd /1" shows now only one Bitmap)
* Print used network interface when CONFIG_NET_MULTI is set
- Added Motorola CPU 8540/8560 support (cpu/85xx)
- Added Motorola MPC8540ADS board support (board/mpc8540ads)
- Added Motorola MPC8560ADS board support (board/mpc8560ads)
* Minor code cleanup
- allow for longer timeouts for USB mass storage devices
* Patch by Denis Peter, 11 Sep 2003:
- fix USB data pointer assignment for bulk only transfer.
- prevent to display erased directories in FAT filesystem.
* Change output format for NAND flash - make it look like for other
memory, too
applications: instead of using (PPC-specific) system calls we now
use a jump table; please see doc/README.standalone for details
* Patch by Dave Westwood, 24 Jul 2003:
added support for Unity OS (a proprietary OS)
- Correct flash and JFFS2 support for MPC8260ADS
- fix PVR values and clock generation for PowerQUICC II family
(8270/8275/8280)
* Patch by Bernhard Kuhn, 08 Jul 2003:
- add support for M68K targets
* Patch by Ken Chou, 3 Jul:
- Fix PCI config table for A3000
- Fix iobase for natsemi.c
(PCI_BASE_ADDRESS_0 is the IO base register for DP83815)
* Allow to enable "slow" POST routines by key press on power-on
* Fix temperature dependend switching of LCD backlight on LWMON
* Tweak output format for LWMON
- remove trailing white space, trailing empty lines, C++ comments, etc.
- split cmd_boot.c (separate cmd_bdinfo.c and cmd_load.c)
* Patches by Kenneth Johansson, 25 Jun 2003:
- major rework of command structure
(work done mostly by Michal Cendrowski and Joakim Kristiansen)
- Hymod board database mods: add "who" field and new xilinx chip types
- provide new "init_cmd_timeout()" function so code external to
"common/main.c" can use the "reset_cmd_timeout()" function before
entering the main loop
- add DTT support for adm1021 (new file dtt/adm1021.c; config
slightly different. see include/configs/hymod.h for an example
(requires CONFIG_DTT_ADM1021, CONFIG_DTT_SENSORS, and
CFG_DTT_ADM1021 defined)
- add new "eeprom_probe()" function which has similar args and
behaves in a similar way to "eeprom_read()" etc.
- add 8260 FCC ethernet loopback code (new "eth_loopback_test()"
function which is enabled by defining CONFIG_ETHER_LOOPBACK_TEST)
- gdbtools copyright update
- ensure that set_msr() executes the "sync" and "isync" instructions
after the "mtmsr" instruction in cpu/mpc8260/interrupts.c
- 8260 I/O ports fix: Open Drain should be set last when configuring
- add SIU IRQ defines for 8260
- allow LDSCRIPT override and OBJCFLAGS initialization: change to
config.mk to allow board configurations to override the GNU
linker script, selected via the LDSCRIPT, make variable, and to
give an initial value to the OBJCFLAGS make variable
- 8260 i2c enhancement:
o correctly extends the timeout depending on the size of all
queued messages for both transmit and receive
o will not continue with receive if transmit times out
o ensures that the error callback is done for all queued tx
and rx messages
o correctly detects both tx and rx timeouts, only delivers one to
the callback, and does not overwrite an earlier error
o logic in i2c_probe now correct
- add "vprintf()" function so that "panic()" function can be
technically correct
- many Hymod board changes
- Added support for custom keyboards, initialized by defining a
board-specific drv_keyboard_init as well as defining CONFIG_KEYBOARD .
- Added support for the RBC823 board.
- cpu/mpc8xx/lcd.c now automatically calculates the
Horizontal Pixel Count field.
* Fix alignment problem in BOOTP (dhcp_leasetime option)
[pointed out by Nicolas Lacressonnière, 2 Jun 2003]
* Patch by Mark Rakes, 14 May 2003:
add support for Intel e1000 gig cards.
* Patch by Nye Liu, 3 Jun 2003:
fix critical typo in MAMR definition (include/mpc8xx.h)
* Fix requirement to align U-Boot image on 16 kB boundaries on PPC.
* Patch by Klaus Heydeck, 2 Jun 2003
Minor changes for KUP4K configuration
instead CFG_MONITOR_LEN is now only used to determine _at_compile_
_time_ (!) if the environment is embedded within the U-Boot image,
or in a separate flash sector.
* Cleanup CFG_DER #defines in config files (wd maintained only)
Fix problem with only partially cleared .bss segment
* Patch by Rune Torgersen, 12 May 2003:
get PCI to work on a MPC8266ADS board; incorporate change to
cpu/mpc8260/pci.c to enable overrides of PCI memory parameters
* Patch by Keith Outwater, 28 Apr 2003:
- Miscellaneous corrections and additions to GEN860T board specific code.
- Added GEN860_SC variant to GEN860T.
- Miscellaneous corrections to GEN860T documentation.
- Correct duplicate entry in U-Boot CREDITS file.
- Add GEN860T_SC entry in MAINTAINERS file.
- Update CREDITS file with GEN860T_SC info.
* Update Smiths Aerospace addresses in MAINTAINERS file
* Fix error handling in hush's version of "run" command
- Splashscreen support
- modem support
- sysmon support
- temperature dependend enabling of LCD
* Allow booting from old "PPCBoot" disk partitions
* Add support for TQM8255 Board / MPC8255 CPU
- Add port to MPC555/556 microcontrollers
- Add support for cmi customer board with
Intel 28F128J3A, 28F320J3A or 28F640J3A flash.
* Patch by Rick Bronson, 28 Mar 2003:
- fix common/cmd_nand.c
- 16/32 MB and 50/80 MHz support with auto-detection for IP860
- ETH05 and BEDBUG support for CU824
- added support for MicroSys CPC45
- new BOOTROM/FLASH0 and DOC base for PM826
* Patch by Robert Schwebel, 12 Mar 2003:
Fix the chpart command on innokom board
* Name cleanup:
mv include/asm-i386/ppcboot-i386.h include/asm-i386/u-boot-i386.h
s/PPCBoot/U-Boot/ in some files
s/pImage/uImage/ in some files
* Patch by Detlev Zundel, 15 Jan 2003:
Fix '' command line quoting
* Patch by The LEOX team, 19 Jan 2003:
- add support for the ELPT860 board
- add support for Dallas ds164x RTC
Fix misc problems with AmigaOne support
* Patch by Chris Hallinan, 3 Dec 2002:
minor cleanup to the MPC8245 EPIC driver
* Patch by Pierre Aubert , 28 Nov 2002
Add support for external (SIU) interrupts on MPC8xx
* Patch by Pierre Aubert , 28 Nov 2002
Fix nested syscalls bug in standalone applications
* Patch by David Müller, 27 Nov 2002:
fix output of "pciinfo" command for CardBus bridge devices.
* Fix bug in TQM8260 board detection - boards got stuck when board ID
was not readable
Add code for AmigaOne board
(preliminary merge to U-Boot, still WIP)
* Patch by Jon Diekema, 12 Nov 2002:
- Adding URL for IEEE OUI lookup
- Making the autoboot #defines dependent on CONFIG_AUTOBOOT_KEYED
being defined.
- In the CONFIG_EXTRA_ENV_SETTINGS #define, the root-on-initrd and
root-on-nfs macros are designed to switch how the default boot
method gets defined.
