port-sparc/56084: sparc crashdump and savecore(8) not working

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

>Number:         56084
>Category:       port-sparc
>Synopsis:       sparc crashdump and savecore(8) not working
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    port-sparc-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Mar 29 14:00:00 +0000 2021
>Originator:     Izumi Tsutsui
>Release:        NetBSD 9.1
>Organization:
>Environment:
System: NetBSD 9.1 (GENERIC) #0: Sun Oct 18 19:24:30 UTC 2020
 mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/sparc/compile/GENERIC
Architecture: sparc
Machine: sparc
>Description:
It looks kernel crashdump and savecore(8) don't work as expected
on NetBSD/sparc 9.1.

>How-To-Repeat:
reboot -d on NetBSD/sparc 9.1

# reboot -d
 :
syncing disks... done
Frame pointer is at 0xf38ced10
 :
dumping to dev 7,1 offset 186991
dump succeeded

 :

# savecore
savecore: dump_exists:471: kvm_read newdumpmag: _kvm_kvatop(f05132d8)
#

>Fix:
No idea. There is no "dumping MBs" logs:
---
void
dumpsys(void)
{

[snip]

		for (; i < mp->len; i += n) {
			n = mp->len - i;
			if (n > BYTES_PER_DUMP)
				 n = BYTES_PER_DUMP;

			/* print out how many MBs we have dumped */
			if (i && (i % (1024*1024)) == 0)
				printf_nolog("%d ", i / (1024*1024));

			(void) pmap_map(dumpspace, maddr, maddr + n,
					VM_PROT_READ);
			error = (*dump)(dumpdev, blkno,
					(void *)dumpspace, (int)n);
			pmap_kremove(dumpspace, n);
			pmap_update(pmap_kernel());
---

so something wrong in pmap_dumpsize() in machdep.c?