/dev/ksyms under Xen-4.7

[marcotte%panix.com@localhost (Brian Marcotte)]

I upgraded some of my systems to Xen 4.7.0 and found that in NetBSD domUs,
/dev/ksyms no longer works:

    # hexdump -C /dev/ksyms
    hexdump: /dev/ksyms: Device not configured
    hexdump: /dev/ksyms: Bad file descriptor

This prevents some utilities like fstat or lsof from working.

The NetBSD domUs are 6.1.5, 7.0, or current (from NetBSD-daily).
The dom0s are Linux 4.1 or 4.7.

The kernel output, below, doesn't give me any indication why this is.

- Brian

----------------------

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NetBSD 7.0 (PANIX-XEN-STD) #4: Tue Jan 19 00:56:12 EST 2016
	root%juggler.panix.com@localhost:/misc/obj/misc/devel/netbsd/7.0/src/sys/arch/i386/compile/PANIX-XEN-STD
total memory = 1400 MB
avail memory = 1367 MB
kern.module.path=/stand/i386pae-xen/7.0/modules
timecounter: Timecounters tick every 10.000 msec
mainbus0 (root)
hypervisor0 at mainbus0: Xen version 4.7.0
VIRQ_DEBUG interrupt using event channel 3
vcpu0 at hypervisor0: Intel(R) Xeon(R) CPU           X3430  @ 2.40GHz, id 0x106e5
xenbus0 at hypervisor0: Xen Virtual Bus Interface
xencons0 at hypervisor0: Xen Virtual Console Driver
xencons0: console major 143, unit 0
xencons0: using event channel 2
timecounter: Timecounter "clockinterrupt" frequency 100 Hz quality 0
timecounter: Timecounter "xen_system_time" frequency 1000000000 Hz quality 10000
Xen clock: using event channel 5
xenbus0: using event channel 1
xenbus: can't get state for device/suspend/event-channel (2)
xbd0 at xenbus0 id 0: Xen Virtual Block Device Interface
xbd0: using event channel 6
xbd1 at xenbus0 id 1: Xen Virtual Block Device Interface
xbd1: using event channel 7
xbd3 at xenbus0 id 3: Xen Virtual Block Device Interface
xbd3: using event channel 8
xbd4 at xenbus0 id 4: Xen Virtual Block Device Interface
xbd4: using event channel 9
xbd5 at xenbus0 id 5: Xen Virtual Block Device Interface
xbd5: using event channel 10
xbd6 at xenbus0 id 6: Xen Virtual Block Device Interface
xbd6: using event channel 11
xbd7 at xenbus0 id 7: Xen Virtual Block Device Interface
xbd7: using event channel 12
xbd8 at xenbus0 id 8: Xen Virtual Block Device Interface
xbd8: using event channel 13
xbd9 at xenbus0 id 9: Xen Virtual Block Device Interface
xbd9: using event channel 14
xbd10 at xenbus0 id 10: Xen Virtual Block Device Interface
xbd10: using event channel 15
xennet0 at xenbus0 id 0: Xen Virtual Network Interface
xennet0: MAC address ee:5b:a7:1a:84:d5
xennet0: using event channel 16
balloon0 at xenbus0 id 0: Xen Balloon driver
balloon0: current reservation: 1433600 KiB
xbd0: 2000 MB, 512 bytes/sect x 4096000 sectors
xbd1: 1024 MB, 512 bytes/sect x 2097152 sectors
xbd3: 3726 GB, 512 bytes/sect x 7814029312 sectors
xbd3: GPT GUID: 9230acc9-5766-11e5-8517-ee5ba71a84d5
dk0 at xbd3: 9230ace1-5766-11e5-8517-ee5ba71a84d5
dk0: 7814029239 blocks at 40, type: ffs
xbd4: 1863 GB, 512 bytes/sect x 3907018752 sectors
xbd5: 1863 GB, 512 bytes/sect x 3907018752 sectors
xbd6: 4657 GB, 512 bytes/sect x 9767526400 sectors
xbd6: GPT GUID: 21887b12-dacf-11e4-8799-ee5ba71a84d5
dk1 at xbd6: 21887b2e-dacf-11e4-8799-ee5ba71a84d5
dk1: 9767526293 blocks at 40, type: ffs
xbd7: 2794 GB, 512 bytes/sect x 5860524032 sectors
xbd7: GPT GUID: 446c54dd-dc7c-11e4-8762-ee5ba71a84d5
dk2 at xbd7: 446c54f9-dc7c-11e4-8762-ee5ba71a84d5
dk2: 5860523952 blocks at 40, type: ffs
xbd8: 1863 GB, 512 bytes/sect x 3907018752 sectors
xbd9: 1863 GB, 512 bytes/sect x 3907010560 sectors
xbd10: 200 GB, 512 bytes/sect x 419430400 sectors
boot device: xbd0
xennet0: using RX copy mode
root on xbd0a dumps on xbd0b
root file system type: ffs
xenbus: can't get state for device/suspend/event-channel (2)
balloon0: current reservation: 358400 pages => target: 358400 pages
ignore shutdown request: 
xenbus: can't get state for device/suspend/event-channel (2)