allow "root=xxx" command line to override platform defaults.

PR#57324 shows that on broadcom evbarm systems the default root
is no longer chosen, even when specified on the command line.

sc.dying and mlelstv pointed out that revision 1.24 made this
function skip parsing "root=" if already set, which was not what
i expected to happen anywhere here (and it works fine on FDT and
UEFI boots.)

revert that part of 1.24.

XXX: pullup-10.


(while this is it's own bug, it points out that
bcm283x_platform_device_register() currently will set
booted_device to the first ld@sdmmc found, even if that device was
not involved with booting. while fixing this would be nice, it
wouldn't have helped with this setup -- choosing ld@sdmmc is the
right answer in eg PR#57324 at this point, so having it set in
this case should be fine, and then overrideable via root=.)

fix root detection on evbarm when raid is involved

there are several problems solved in this change:
- lots of work was re-done when we already have determined the
device booted from, so several new early returns introduced
if booted_device has been set
- due to the lack of cpu_bootconf(), raidframe softroot would
override "root=xxx" on the boot command line (note that
platforms that use eg, device_register() to detect the boot
device are not affected by this issue as they find the
boot device much earlier.)
- in the new cpu_bootconf(), switch the order of the platform
boot-config with the set_root_device() call. this avoids a
problem where "root=xxx" is checked after automated methods,
and is thus ignored.
- in fdt_detect_root_device(), remove the code to add "root=xxx""
string to the boot_args[] that would be later parsed by the
set_root_device() call, and simply set booted_device and, for
mbr installs, booted_partition directly. also, for any
successful call, perform an early return.
- define __HAVE_CPU_BOOTCONF so early boot calls cpu_bootconf().


tested on:
- rockpro64 booting from emmc, sata (big, and little endian)
- rockpro64 loading kernel from msdos partition
- rockpro64 booting from network (fails to auto-detect, with or
without this change)
- quartz64 booting from nvme
- lx2k booting from nvme

XXX: pullup-10

branches: 1.23.18;
implement boot -d for arm64.

could be done at the end of initarm() except it hangs currently.
this gets you a db> prompt before devices are configured.

ok @skrll.

branches: 1.22.12;
Add evbarm_cpu_rootconf callback for hooking into cpu_rootconf

branches: 1.21.2; 1.21.4;
splserial is an alias for splhigh now. No need to splhigh twice.

Don't assume that the root autoconfiguration device is named "mainbus".

Don't modify command line buffer but create a copy of the root argument.

branches: 1.18.2;
If the boot argument "root" cannot be parsed as a device name, pass the
string untranslated to MI code. Due to limits in the boot argument parser
the string is terminated by whitespace.

Define and implement device_register_post_config() hook analog to the
device_register() hook.

Already found on sparc64 and librump. Tested compilation and running of
machines with and without the hook defined.

branches: 1.16.2; 1.16.10;
Correct off-by-one in validation of booted partition number.

Add get_device(), set_root_device() to get root device via bootargs.
This is same as some other archs. PR#47250.

split device_t/softc for all remaining drivers.
replace "struct device *" with "device_t".
use device_xname(), device_unit(), etc.

branches: 1.13.2;
Do not call setroot() from MD code and from MI code, which has
unwanted sideeffects in the RB_ASKNAME case. This fixes PR/46732.

No longer wrap MD cpu_rootconf(), as hp300 port stores reboot information
as a side effect. Instead call MI rootconf() from MD code which makes
rootconf() now a wrapper to setroot().

Adjust several MD routines to set the global booted_device,booted_partition
variables instead of passing partial information to setroot().

Make cpu_rootconf(9) describe the calling order.

branches: 1.12.34; 1.12.40;
Remove clause 3 and 4 from TNF licenses

branches: 1.11.14; 1.11.16; 1.11.18;
Interrupt handling changes, in discussion since February:

- Reduce available SPL levels for hardware devices to none, vm, sched, high.
- Acquire kernel_lock only for interrupts at IPL_VM.
- Implement threaded soft interrupts.

branches: 1.10.30; 1.10.46; 1.10.48; 1.10.50; 1.10.56;
merge ktrace-lwp.

branches: 1.9.12;
Centralize the declaration of booted_device and booted_partition.

__KERNEL_RCSID()

Do an splhigh() before doing splserial(), in the event that
serial isn't actually higher than high.

Use splserial() instead of splhigh() to block interrupt during
autoconfiguration. XXX We really need an splextreme() for when
we really mean "block everything".

Provide a hook for board-specific code to register a device_register()
function.

branches: 1.4.2;
Go to splhigh() before doing autoconfiguration.

Use aprint_normal() to report the boot device.

branches: 1.2.2;
New interrupt framework for NetBSD/evbarm, and accompanying new
interrupt code for the IQ80310 board support package.

XXX The Integrator board support package still uses the old-style
arm32 interrupt code, so some compatibility hacks have been added
for it. When the Integrator uses new-style interrupts, those hacks
can go away.

branches: 1.1.6;
more evbarm files (very incomplete).

This file is not used.

branches: 1.2.4;
Don't define pcb_* register macros.
pcb_sp macro conflicts with sys/netinet6/ipsec.c.

branches: 1.1.2;
more evbarm files (very incomplete).

Remove old and never used evbarm/initarm_common. Please use
arm32/arm32_boot.c:initarm_common

add missing arg to cpu_setttb().

branches: 1.11.2;
Fix more -fno-common fallout.
Move more variables to common locations.

branches: 1.10.12;
Use cpu_* prefix to call cpu_* functions (setttb() -> cpu_setttb()); no
functional changes.

- Use uvm_lwp_setuarea() instead of directly setting address to lwp_t::l_addr.
- Replace most remaining uses of l_addr with uvm_lwp_getuarea() or lwp_getpcb().
- Amend assembly in ports where it accesses PCB via struct user.
- Rename L_ADDR to L_PCB in few places. Reduce sys/user.h inclusions.

Kill proc0paddr. Use lwp0.l_addr instead.

Remove all declarations of physmem from sys/arch. Add an include of
<sys/systm.h> to the one file that did not already contain it.
This now means that physmem can be changed by updating systm.h and uvm_page.c
(excluding fixing printfs)

branches: 1.6.10;
Remove arm support for IPKDB.

It hasn't worked since arm was broken out from arm32 in Jan 2001, and
no-one has noticed or cared to fix it.

branches: 1.5.46; 1.5.50; 1.5.56; 1.5.64;
merge ktrace-lwp.

branches: 1.4.10;
Fix comments regarding configration bounaries

Fix comments slighly

__KERNEL_RCSID()

branches: 1.1.2;
Add support for ARM32_PMAP_NEW and ARM32_NEW_VM_LAYOUT to the iq80321 port.

Remove old and never used evbarm/initarm_common. Please use
arm32/arm32_boot.c:initarm_common

branches: 1.1.142; 1.1.152;
Add support for ARM32_PMAP_NEW and ARM32_NEW_VM_LAYOUT to the iq80321 port.

Move the generic ARM soft interrupt code into a generic place.

Generic soft interrupt support for the evbarm port. Two caveats:
* This is not currently used by the in-tree evbarm interrupt code. New
interrupt code will appear "soon" which makes use of this file.
* This file will probably move to a generic ARM location eventually.