build: Define _BOOT_MODE once and for all in ArchitectureRules+BootRules.

Previously it was spread all around the tree, and was not defined
consistently for all boot objects (there were a number of boot modules
which did not define it, but did include headers which checked for it.)

Now, as it is handled in SetupBoot which is invoked for all boot objects,
it will be applied consistently throughout. We can thus drop the manual
additions of it from all Jamfiles.

boot/efi: factor out generic mmu functions

This change moves the common functions related to EFI memory map
to arch/generic for arm, arm64, x86.

riscv64 and x86_64 shall be handled separately as they use some
more architecture-specific logic:
* riscv64 needs special treatment for the M-mode resident code
located at 0x80000000 which is reported as available in the
EFI memory map provided by u-boot.
* x86_64 has a slightly different logic for building the
memory regions list so some additional rework and testing will be
needed before it can be unified with the generic mmu functions.

Change-Id: I430c84dfc693c5b6f04c170dec8ffb1db2c2ace1
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5694
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

boot/efi/arm: flush caches before jump to trampoline

Change-Id: Ia7af285f1c3b988828482ff0cd78a416cf51c2c2
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5196
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>

boot/arm: move system_time and spin to platform

Add fake implementation for system_time()
Implement spin() using EFI boot services

Change-Id: Ib69b851780bd03624ce4e19d725dd319f6640601
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4964
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Fredrik Holmqvist <fredrik.holmqvist@gmail.com>

boot/efi: introduce arch_dtb

Change-Id: Iff9e4198aca706097889faf51e9559fe551126ad
Reviewed-on: https://review.haiku-os.org/c/haiku/+/4782
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>

arm: kernel link cleanup and fixes

* Removes several previous hacks, and makes kernel loading
by our bootloader more reliable.
* Long list of "Couldn't find both text and data" errors
no gone in our bootloader as it loads our kernel

Change-Id: Ic9f5ed44975d41fb22d7ab19536261432abe84ba
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3444
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>
Reviewed-by: Fredrik Holmqvist <fredrik.holmqvist@gmail.com>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

boot/efi: Begin working on loading kernel_arm

Change-Id: I5c71f061fab2215f3978a39d87c2d2a686a2c7bc
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3107
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

efi: Ensure MultiBootSubDirSetup runs in arch directories

* Otherwise, important HAIKU_BOOT_* flags don't make it into
the build commands.
* Ensure any external sources used by EFI get recompiled
vs reused due to potential differences in wchar length
(EFI dictates short-wchar, but no wchar's in our code)

Change-Id: I7a4a0347d39239c73fa510378e048f51be1cd360
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2965
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

system/boot/efi: Tweaks to get arm efi further

* Store gFDT as a global in efi to appease non-x86
* gFDT might need refactored out of fdt bus_manager?

Change-Id: I3fb1be04ceb696677aa5476381786c36adc6fc0a

efi/arm: Begin stubbing out the essentials, add fdt library

* We *might* no longer need FDT knowledge in the bootloader?
* For now though, arm sources reference gFDT, so we need it.
* Need to move away from lazy gFDT and store in arch_kernel_args.
(which is next and will be a larger commit)

Change-Id: I77cce0fc645143b78a7fd9f50ac8b96c97b5c862
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2268
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

efi: Refactor our EFI code to use fuchsia's cleaner EFI headers.

* Drop gnu-efi

Change-Id: Ib601fc8ced49b18281b6b98cf861a5aef1b9c065
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2026
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

kernel/boot/efi: Continue breaking apart arch-specific code; hpet

* Move x86 hpet behind timer interface.
* Add a few if x86,x86_64 macros to start.cpp.

Change-Id: I583ec1b064785182e6d48dfbcd91b1bb2ead4b44
Reviewed-on: https://review.haiku-os.org/c/haiku/+/1929
Reviewed-by: Alex von Gluck IV <kallisti5@unixzen.com>