xref: /freebsd-14.2/sys/arm/arm/machdep.c (revision 685dc743)
1 /*	$NetBSD: arm32_machdep.c,v 1.44 2004/03/24 15:34:47 atatat Exp $	*/
2 
3 /*-
4  * SPDX-License-Identifier: BSD-4-Clause
5  *
6  * Copyright (c) 2004 Olivier Houchard
7  * Copyright (c) 1994-1998 Mark Brinicombe.
8  * Copyright (c) 1994 Brini.
9  * All rights reserved.
10  *
11  * This code is derived from software written for Brini by Mark Brinicombe
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1. Redistributions of source code must retain the above copyright
17  *    notice, this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  * 3. All advertising materials mentioning features or use of this software
22  *    must display the following acknowledgement:
23  *	This product includes software developed by Mark Brinicombe
24  *	for the NetBSD Project.
25  * 4. The name of the company nor the name of the author may be used to
26  *    endorse or promote products derived from this software without specific
27  *    prior written permission.
28  *
29  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
30  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
31  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
32  * IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
33  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
34  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
35  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39  * SUCH DAMAGE.
40  *
41  * Machine dependent functions for kernel setup
42  *
43  * Created      : 17/09/94
44  * Updated	: 18/04/01 updated for new wscons
45  */
46 
47 #include "opt_ddb.h"
48 #include "opt_kstack_pages.h"
49 #include "opt_platform.h"
50 #include "opt_sched.h"
51 
52 #include <sys/cdefs.h>
53 #include <sys/param.h>
54 #include <sys/buf.h>
55 #include <sys/bus.h>
56 #include <sys/cons.h>
57 #include <sys/cpu.h>
58 #include <sys/devmap.h>
59 #include <sys/efi.h>
60 #include <sys/imgact.h>
61 #include <sys/kdb.h>
62 #include <sys/kernel.h>
63 #include <sys/ktr.h>
64 #include <sys/linker.h>
65 #include <sys/msgbuf.h>
66 #include <sys/physmem.h>
67 #include <sys/reboot.h>
68 #include <sys/rwlock.h>
69 #include <sys/sched.h>
70 #include <sys/syscallsubr.h>
71 #include <sys/sysent.h>
72 #include <sys/sysproto.h>
73 #include <sys/vmmeter.h>
74 
75 #include <vm/vm_object.h>
76 #include <vm/vm_page.h>
77 #include <vm/vm_pager.h>
78 
79 #include <machine/asm.h>
80 #include <machine/debug_monitor.h>
81 #include <machine/machdep.h>
82 #include <machine/metadata.h>
83 #include <machine/pcb.h>
84 #include <machine/platform.h>
85 #include <machine/sysarch.h>
86 #include <machine/undefined.h>
87 #include <machine/vfp.h>
88 #include <machine/vmparam.h>
89 
90 #ifdef FDT
91 #include <dev/fdt/fdt_common.h>
92 #include <machine/ofw_machdep.h>
93 #endif
94 
95 #ifdef DEBUG
96 #define	debugf(fmt, args...) printf(fmt, ##args)
97 #else
98 #define	debugf(fmt, args...)
99 #endif
100 
101 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
102     defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) || \
103     defined(COMPAT_FREEBSD9)
104 #error FreeBSD/arm doesn't provide compatibility with releases prior to 10
105 #endif
106 
107 
108 #if __ARM_ARCH < 6
109 #error FreeBSD requires ARMv6 or later
110 #endif
111 
112 struct pcpu __pcpu[MAXCPU];
113 struct pcpu *pcpup = &__pcpu[0];
114 
115 static struct trapframe proc0_tf;
116 uint32_t cpu_reset_address = 0;
117 int cold = 1;
118 vm_offset_t vector_page;
119 
120 /* The address at which the kernel was loaded.  Set early in initarm(). */
121 vm_paddr_t arm_physmem_kernaddr;
122 
123 extern int *end;
124 
125 #ifdef FDT
126 vm_paddr_t pmap_pa;
127 vm_offset_t systempage;
128 vm_offset_t irqstack;
129 vm_offset_t undstack;
130 vm_offset_t abtstack;
131 #endif /* FDT */
132 
133 #ifdef PLATFORM
134 static delay_func *delay_impl;
135 static void *delay_arg;
136 #endif
137 
138 struct kva_md_info kmi;
139 /*
140  * arm32_vector_init:
141  *
142  *	Initialize the vector page, and select whether or not to
143  *	relocate the vectors.
144  *
145  *	NOTE: We expect the vector page to be mapped at its expected
146  *	destination.
147  */
148 
149 extern unsigned int page0[], page0_data[];
150 void
arm_vector_init(vm_offset_t va,int which)151 arm_vector_init(vm_offset_t va, int which)
152 {
153 	unsigned int *vectors = (int *) va;
154 	unsigned int *vectors_data = vectors + (page0_data - page0);
155 	int vec;
156 
157 	/*
158 	 * Loop through the vectors we're taking over, and copy the
159 	 * vector's insn and data word.
160 	 */
161 	for (vec = 0; vec < ARM_NVEC; vec++) {
162 		if ((which & (1 << vec)) == 0) {
163 			/* Don't want to take over this vector. */
164 			continue;
165 		}
166 		vectors[vec] = page0[vec];
167 		vectors_data[vec] = page0_data[vec];
168 	}
169 
170 	/* Now sync the vectors. */
171 	icache_sync(va, (ARM_NVEC * 2) * sizeof(u_int));
172 
173 	vector_page = va;
174 }
175 
176 static void
cpu_startup(void * dummy)177 cpu_startup(void *dummy)
178 {
179 	struct pcb *pcb = thread0.td_pcb;
180 	const unsigned int mbyte = 1024 * 1024;
181 
182 	identify_arm_cpu();
183 
184 	vm_ksubmap_init(&kmi);
185 
186 	/*
187 	 * Display the RAM layout.
188 	 */
189 	printf("real memory  = %ju (%ju MB)\n",
190 	    (uintmax_t)arm32_ptob(realmem),
191 	    (uintmax_t)arm32_ptob(realmem) / mbyte);
192 	printf("avail memory = %ju (%ju MB)\n",
193 	    (uintmax_t)arm32_ptob(vm_free_count()),
194 	    (uintmax_t)arm32_ptob(vm_free_count()) / mbyte);
195 	if (bootverbose) {
196 		physmem_print_tables();
197 		devmap_print_table();
198 	}
199 
200 	bufinit();
201 	vm_pager_bufferinit();
202 	pcb->pcb_regs.sf_sp = (u_int)thread0.td_kstack +
203 	    USPACE_SVC_STACK_TOP;
204 	pmap_set_pcb_pagedir(kernel_pmap, pcb);
205 }
206 
207 SYSINIT(cpu, SI_SUB_CPU, SI_ORDER_FIRST, cpu_startup, NULL);
208 
209 /*
210  * Flush the D-cache for non-DMA I/O so that the I-cache can
211  * be made coherent later.
212  */
213 void
cpu_flush_dcache(void * ptr,size_t len)214 cpu_flush_dcache(void *ptr, size_t len)
215 {
216 
217 	dcache_wb_poc((vm_offset_t)ptr, (vm_paddr_t)vtophys(ptr), len);
218 }
219 
220 /* Get current clock frequency for the given cpu id. */
221 int
cpu_est_clockrate(int cpu_id,uint64_t * rate)222 cpu_est_clockrate(int cpu_id, uint64_t *rate)
223 {
224 	struct pcpu *pc;
225 
226 	pc = pcpu_find(cpu_id);
227 	if (pc == NULL || rate == NULL)
228 		return (EINVAL);
229 
230 	if (pc->pc_clock == 0)
231 		return (EOPNOTSUPP);
232 
233 	*rate = pc->pc_clock;
234 
235 	return (0);
236 }
237 
238 void
cpu_idle(int busy)239 cpu_idle(int busy)
240 {
241 
242 	CTR2(KTR_SPARE2, "cpu_idle(%d) at %d", busy, curcpu);
243 	spinlock_enter();
244 	if (!busy)
245 		cpu_idleclock();
246 	if (!sched_runnable())
247 		cpu_sleep(0);
248 	if (!busy)
249 		cpu_activeclock();
250 	spinlock_exit();
251 	CTR2(KTR_SPARE2, "cpu_idle(%d) at %d done", busy, curcpu);
252 }
253 
254 int
cpu_idle_wakeup(int cpu)255 cpu_idle_wakeup(int cpu)
256 {
257 
258 	return (0);
259 }
260 
261 void
cpu_initclocks(void)262 cpu_initclocks(void)
263 {
264 
265 #ifdef SMP
266 	if (PCPU_GET(cpuid) == 0)
267 		cpu_initclocks_bsp();
268 	else
269 		cpu_initclocks_ap();
270 #else
271 	cpu_initclocks_bsp();
272 #endif
273 }
274 
275 #ifdef PLATFORM
276 void
arm_set_delay(delay_func * impl,void * arg)277 arm_set_delay(delay_func *impl, void *arg)
278 {
279 
280 	KASSERT(impl != NULL, ("No DELAY implementation"));
281 	delay_impl = impl;
282 	delay_arg = arg;
283 }
284 
285 void
DELAY(int usec)286 DELAY(int usec)
287 {
288 
289 	TSENTER();
290 	delay_impl(usec, delay_arg);
291 	TSEXIT();
292 }
293 #endif
294 
295 void
cpu_pcpu_init(struct pcpu * pcpu,int cpuid,size_t size)296 cpu_pcpu_init(struct pcpu *pcpu, int cpuid, size_t size)
297 {
298 
299 	pcpu->pc_mpidr = 0xffffffff;
300 }
301 
302 void
spinlock_enter(void)303 spinlock_enter(void)
304 {
305 	struct thread *td;
306 	register_t cspr;
307 
308 	td = curthread;
309 	if (td->td_md.md_spinlock_count == 0) {
310 		cspr = disable_interrupts(PSR_I | PSR_F);
311 		td->td_md.md_spinlock_count = 1;
312 		td->td_md.md_saved_cspr = cspr;
313 		critical_enter();
314 	} else
315 		td->td_md.md_spinlock_count++;
316 }
317 
318 void
spinlock_exit(void)319 spinlock_exit(void)
320 {
321 	struct thread *td;
322 	register_t cspr;
323 
324 	td = curthread;
325 	cspr = td->td_md.md_saved_cspr;
326 	td->td_md.md_spinlock_count--;
327 	if (td->td_md.md_spinlock_count == 0) {
328 		critical_exit();
329 		restore_interrupts(cspr);
330 	}
331 }
332 
333 /*
334  * Construct a PCB from a trapframe. This is called from kdb_trap() where
335  * we want to start a backtrace from the function that caused us to enter
336  * the debugger. We have the context in the trapframe, but base the trace
337  * on the PCB. The PCB doesn't have to be perfect, as long as it contains
338  * enough for a backtrace.
339  */
340 void
makectx(struct trapframe * tf,struct pcb * pcb)341 makectx(struct trapframe *tf, struct pcb *pcb)
342 {
343 	pcb->pcb_regs.sf_r4 = tf->tf_r4;
344 	pcb->pcb_regs.sf_r5 = tf->tf_r5;
345 	pcb->pcb_regs.sf_r6 = tf->tf_r6;
346 	pcb->pcb_regs.sf_r7 = tf->tf_r7;
347 	pcb->pcb_regs.sf_r8 = tf->tf_r8;
348 	pcb->pcb_regs.sf_r9 = tf->tf_r9;
349 	pcb->pcb_regs.sf_r10 = tf->tf_r10;
350 	pcb->pcb_regs.sf_r11 = tf->tf_r11;
351 	pcb->pcb_regs.sf_r12 = tf->tf_r12;
352 	pcb->pcb_regs.sf_pc = tf->tf_pc;
353 	pcb->pcb_regs.sf_lr = tf->tf_usr_lr;
354 	pcb->pcb_regs.sf_sp = tf->tf_usr_sp;
355 }
356 
357 void
pcpu0_init(void)358 pcpu0_init(void)
359 {
360 	set_curthread(&thread0);
361 	pcpu_init(pcpup, 0, sizeof(struct pcpu));
362 	pcpup->pc_mpidr = cp15_mpidr_get() & 0xFFFFFF;
363 	PCPU_SET(curthread, &thread0);
364 }
365 
366 /*
367  * Initialize proc0
368  */
369 void
init_proc0(vm_offset_t kstack)370 init_proc0(vm_offset_t kstack)
371 {
372 	proc_linkup0(&proc0, &thread0);
373 	thread0.td_kstack = kstack;
374 	thread0.td_kstack_pages = kstack_pages;
375 	thread0.td_pcb = (struct pcb *)(thread0.td_kstack +
376 	    thread0.td_kstack_pages * PAGE_SIZE) - 1;
377 	thread0.td_pcb->pcb_flags = 0;
378 	thread0.td_pcb->pcb_fpflags = 0;
379 	thread0.td_pcb->pcb_vfpcpu = -1;
380 	thread0.td_pcb->pcb_vfpstate.fpscr = VFPSCR_DN;
381 	thread0.td_pcb->pcb_vfpsaved = &thread0.td_pcb->pcb_vfpstate;
382 	thread0.td_frame = &proc0_tf;
383 	pcpup->pc_curpcb = thread0.td_pcb;
384 }
385 
386 void
set_stackptrs(int cpu)387 set_stackptrs(int cpu)
388 {
389 
390 	set_stackptr(PSR_IRQ32_MODE,
391 	    irqstack + ((IRQ_STACK_SIZE * PAGE_SIZE) * (cpu + 1)));
392 	set_stackptr(PSR_ABT32_MODE,
393 	    abtstack + ((ABT_STACK_SIZE * PAGE_SIZE) * (cpu + 1)));
394 	set_stackptr(PSR_UND32_MODE,
395 	    undstack + ((UND_STACK_SIZE * PAGE_SIZE) * (cpu + 1)));
396 }
397 
398 static void
arm_kdb_init(void)399 arm_kdb_init(void)
400 {
401 
402 	kdb_init();
403 #ifdef KDB
404 	if (boothowto & RB_KDB)
405 		kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
406 #endif
407 }
408 
409 #ifdef FDT
410 void *
initarm(struct arm_boot_params * abp)411 initarm(struct arm_boot_params *abp)
412 {
413 	struct mem_region mem_regions[FDT_MEM_REGIONS];
414 	vm_paddr_t lastaddr;
415 	vm_offset_t dtbp, kernelstack, dpcpu;
416 	char *env;
417 	void *kmdp;
418 	int err_devmap, mem_regions_sz;
419 	phandle_t root;
420 	char dts_version[255];
421 #ifdef EFI
422 	struct efi_map_header *efihdr;
423 #endif
424 
425 	/* get last allocated physical address */
426 	arm_physmem_kernaddr = abp->abp_physaddr;
427 	lastaddr = parse_boot_param(abp) - KERNVIRTADDR + arm_physmem_kernaddr;
428 
429 	set_cpufuncs();
430 	cpuinfo_init();
431 
432 	/*
433 	 * Find the dtb passed in by the boot loader.
434 	 */
435 	kmdp = preload_search_by_type("elf kernel");
436 	dtbp = MD_FETCH(kmdp, MODINFOMD_DTBP, vm_offset_t);
437 #if defined(FDT_DTB_STATIC)
438 	/*
439 	 * In case the device tree blob was not retrieved (from metadata) try
440 	 * to use the statically embedded one.
441 	 */
442 	if (dtbp == (vm_offset_t)NULL)
443 		dtbp = (vm_offset_t)&fdt_static_dtb;
444 #endif
445 
446 	if (OF_install(OFW_FDT, 0) == FALSE)
447 		panic("Cannot install FDT");
448 
449 	if (OF_init((void *)dtbp) != 0)
450 		panic("OF_init failed with the found device tree");
451 
452 #if defined(LINUX_BOOT_ABI)
453 	arm_parse_fdt_bootargs();
454 #endif
455 
456 #ifdef EFI
457 	efihdr = (struct efi_map_header *)preload_search_info(kmdp,
458 	    MODINFO_METADATA | MODINFOMD_EFI_MAP);
459 	if (efihdr != NULL) {
460 		arm_add_efi_map_entries(efihdr, mem_regions, &mem_regions_sz);
461 	} else
462 #endif
463 	{
464 		/* Grab physical memory regions information from device tree. */
465 		if (fdt_get_mem_regions(mem_regions, &mem_regions_sz,NULL) != 0)
466 			panic("Cannot get physical memory regions");
467 	}
468 	physmem_hardware_regions(mem_regions, mem_regions_sz);
469 
470 	/* Grab reserved memory regions information from device tree. */
471 	if (fdt_get_reserved_regions(mem_regions, &mem_regions_sz) == 0)
472 		physmem_exclude_regions(mem_regions, mem_regions_sz,
473 		    EXFLAG_NODUMP | EXFLAG_NOALLOC);
474 
475 	/*
476 	 * Set TEX remapping registers.
477 	 * Setup kernel page tables and switch to kernel L1 page table.
478 	 */
479 	pmap_set_tex();
480 	pmap_bootstrap_prepare(lastaddr);
481 
482 	/*
483 	 * If EARLY_PRINTF support is enabled, we need to re-establish the
484 	 * mapping after pmap_bootstrap_prepare() switches to new page tables.
485 	 * Note that we can only do the remapping if the VA is outside the
486 	 * kernel, now that we have real virtual (not VA=PA) mappings in effect.
487 	 * Early printf does not work between the time pmap_set_tex() does
488 	 * cp15_prrr_set() and this code remaps the VA.
489 	 */
490 #if defined(EARLY_PRINTF) && defined(SOCDEV_PA) && defined(SOCDEV_VA) && SOCDEV_VA < KERNBASE
491 	pmap_preboot_map_attr(SOCDEV_PA, SOCDEV_VA, 1024 * 1024,
492 	    VM_PROT_READ | VM_PROT_WRITE, VM_MEMATTR_DEVICE);
493 #endif
494 
495 	/*
496 	 * Now that proper page tables are installed, call cpu_setup() to enable
497 	 * instruction and data caches and other chip-specific features.
498 	 */
499 	cpu_setup();
500 
501 	/* Platform-specific initialisation */
502 	platform_probe_and_attach();
503 	pcpu0_init();
504 
505 	/* Do basic tuning, hz etc */
506 	init_param1();
507 
508 	/*
509 	 * Allocate a page for the system page mapped to 0xffff0000
510 	 * This page will just contain the system vectors and can be
511 	 * shared by all processes.
512 	 */
513 	systempage = pmap_preboot_get_pages(1);
514 
515 	/* Map the vector page. */
516 	pmap_preboot_map_pages(systempage, ARM_VECTORS_HIGH,  1);
517 	if (virtual_end >= ARM_VECTORS_HIGH)
518 		virtual_end = ARM_VECTORS_HIGH - 1;
519 
520 	/* Allocate dynamic per-cpu area. */
521 	dpcpu = pmap_preboot_get_vpages(DPCPU_SIZE / PAGE_SIZE);
522 	dpcpu_init((void *)dpcpu, 0);
523 
524 	/* Allocate stacks for all modes */
525 	irqstack    = pmap_preboot_get_vpages(IRQ_STACK_SIZE * MAXCPU);
526 	abtstack    = pmap_preboot_get_vpages(ABT_STACK_SIZE * MAXCPU);
527 	undstack    = pmap_preboot_get_vpages(UND_STACK_SIZE * MAXCPU );
528 	kernelstack = pmap_preboot_get_vpages(kstack_pages);
529 
530 	/* Allocate message buffer. */
531 	msgbufp = (void *)pmap_preboot_get_vpages(
532 	    round_page(msgbufsize) / PAGE_SIZE);
533 
534 	/*
535 	 * Pages were allocated during the secondary bootstrap for the
536 	 * stacks for different CPU modes.
537 	 * We must now set the r13 registers in the different CPU modes to
538 	 * point to these stacks.
539 	 * Since the ARM stacks use STMFD etc. we must set r13 to the top end
540 	 * of the stack memory.
541 	 */
542 	set_stackptrs(0);
543 	mutex_init();
544 
545 	/* Establish static device mappings. */
546 	err_devmap = platform_devmap_init();
547 	devmap_bootstrap(0, NULL);
548 	vm_max_kernel_address = platform_lastaddr();
549 
550 	/*
551 	 * Only after the SOC registers block is mapped we can perform device
552 	 * tree fixups, as they may attempt to read parameters from hardware.
553 	 */
554 	OF_interpret("perform-fixup", 0);
555 	platform_gpio_init();
556 	cninit();
557 
558 	/*
559 	 * If we made a mapping for EARLY_PRINTF after pmap_bootstrap_prepare(),
560 	 * undo it now that the normal console printf works.
561 	 */
562 #if defined(EARLY_PRINTF) && defined(SOCDEV_PA) && defined(SOCDEV_VA) && SOCDEV_VA < KERNBASE
563 	pmap_kremove(SOCDEV_VA);
564 #endif
565 
566 	debugf("initarm: console initialized\n");
567 	debugf(" arg1 kmdp = 0x%08x\n", (uint32_t)kmdp);
568 	debugf(" boothowto = 0x%08x\n", boothowto);
569 	debugf(" dtbp = 0x%08x\n", (uint32_t)dtbp);
570 	debugf(" lastaddr1: 0x%08x\n", lastaddr);
571 	arm_print_kenv();
572 
573 	env = kern_getenv("kernelname");
574 	if (env != NULL)
575 		strlcpy(kernelname, env, sizeof(kernelname));
576 
577 	if (err_devmap != 0)
578 		printf("WARNING: could not fully configure devmap, error=%d\n",
579 		    err_devmap);
580 
581 	platform_late_init();
582 
583 	root = OF_finddevice("/");
584 	if (OF_getprop(root, "freebsd,dts-version", dts_version, sizeof(dts_version)) > 0) {
585 		if (strcmp(LINUX_DTS_VERSION, dts_version) != 0)
586 			printf("WARNING: DTB version is %s while kernel expects %s, "
587 			    "please update the DTB in the ESP\n",
588 			    dts_version,
589 			    LINUX_DTS_VERSION);
590 	} else {
591 		printf("WARNING: Cannot find freebsd,dts-version property, "
592 		    "cannot check DTB compliance\n");
593 	}
594 
595 	/*
596 	 * We must now clean the cache again....
597 	 * Cleaning may be done by reading new data to displace any
598 	 * dirty data in the cache. This will have happened in cpu_setttb()
599 	 * but since we are boot strapping the addresses used for the read
600 	 * may have just been remapped and thus the cache could be out
601 	 * of sync. A re-clean after the switch will cure this.
602 	 * After booting there are no gross relocations of the kernel thus
603 	 * this problem will not occur after initarm().
604 	 */
605 	/* Set stack for exception handlers */
606 	undefined_init();
607 	init_proc0(kernelstack);
608 	arm_vector_init(ARM_VECTORS_HIGH, ARM_VEC_ALL);
609 	enable_interrupts(PSR_A);
610 	pmap_bootstrap(0);
611 
612 	/* Exclude the kernel (and all the things we allocated which immediately
613 	 * follow the kernel) from the VM allocation pool but not from crash
614 	 * dumps.  virtual_avail is a global variable which tracks the kva we've
615 	 * "allocated" while setting up pmaps.
616 	 *
617 	 * Prepare the list of physical memory available to the vm subsystem.
618 	 */
619 	physmem_exclude_region(abp->abp_physaddr,
620 		pmap_preboot_get_pages(0) - abp->abp_physaddr, EXFLAG_NOALLOC);
621 	physmem_init_kernel_globals();
622 
623 	init_param2(physmem);
624 	/* Init message buffer. */
625 	msgbufinit(msgbufp, msgbufsize);
626 	dbg_monitor_init();
627 	arm_kdb_init();
628 	/* Apply possible BP hardening. */
629 	cpuinfo_init_bp_hardening();
630 	return ((void *)STACKALIGN(thread0.td_pcb));
631 
632 }
633 #endif /* FDT */
634