Re: running xen on current

[Brian Buhrow <buhrow%nfbcal.org@localhost>]

	hello.  The difference between UEFI and legacy booting is significant.  I'm not sure about
the current state of NetBSD and xen-dom0, but with FreeBSD, legacy booting is required unless
you're running 13-current.  I think NetBSD/xen-dom0 supports UEFI booting, but it requires you
use multiboot mode instead of the standard NetBSD boot mode.  In addition, I think you need to
be running a pretty recent -current, i.e. something since January 1 2021.
	If you can boot your systems in legacy mode, however, NetBSD-9.x/Xen works very well,
except in conjunction with zfs.

Hope that helps.
-Brian

On Apr 15,  9:53am, Patrick Welche wrote:
} Subject: running xen on current
} I have tried and failed to run xen on 3 -current/amd64 systems with
} 3 different failure modes:
} 
} 1) laptop:  xen.gz Building a PV Dom0 / ELF: not an ELF binary -> panic/reboot
} 2) desktop: XEN3_DOM0 panics including PR port-xen/55978
} 3) server:  Trampoline space cannot be allocated; will try fallback -> reboot
} 
} They are all working NetBSD-current/amd64 systems.
} 
} My conclusion was that xen is hopelessly broken, so was quite surprised
} by Greg Wood's thread about the finer points of running a guest OS, given
} that those systems won't even start the host OS.
} 
} I dug out an old desktop, and to my pleasant surprise it booted XEN3_DOM0,
} and I have managed to run some XEN3_DOMUs.
} 
} The difference between the working/broken setups seems to be that the
} working one is "BIOS" booting rather than EFI booting.
} 
} Among all your xen success stories, are any of you EFI booting?
} 
} 
} Cheers,
} 
} Patrick
} 
} 
} =========================================================================
} 
} Some extra gory details
} 
} 1) laptop:
} 
} **** Building a PV Dom0 ****
} ELF: Not an ELF binary
} 
} ***********************************
} Panic on CPU 0:
} Could not set up DOM0 guest OS
} ***********************************
} 
} Reboot in five seconds...
} 
} 
} 2) desktop: selection of panics in addition to PR port-xen/55978
} 
} 
} [  80.9899999] panic: LIST_INSERT_HEAD 0xffffa080073eec28 ../../../../arch/x86/x86/pmap.c:2285
} [  80.9899999] cpu13: Begin traceback...
} [  80.9899999] vpanic() at netbsd:vpanic+0x14a
} [  80.9899999] snprintf() at netbsd:snprintf
} [  80.9899999] pmap_enter_ma() at netbsd:pmap_enter_ma+0x14e7
} [  80.9899999] pmap_enter() at netbsd:pmap_enter+0x32
} [  80.9899999] udv_fault() at netbsd:udv_fault+0x100
} [  80.9899999] uvm_fault_internal() at netbsd:uvm_fault_internal+0x574
} [  80.9899999] trap() at netbsd:trap+0x432
} [  80.9899999] --- trap (number 6) ---
} [  80.9899999] 7a60617787af:
} [  80.9899999] cpu13: End traceback...
} 
} [  75.6599981] panic: kernel diagnostic assertion "ncp->nc_dvp == dvp" failed: file "../../../../kern/vfs_cache.c", line 432 
} [  75.6599981] cpu0: Begin traceback...
} [  75.6599981] vpanic() at netbsd:vpanic+0x14a
} [  75.6599981] kern_assert() at netbsd:kern_assert+0x48
} [  75.6599981] cache_lookup_entry() at netbsd:cache_lookup_entry+0xde
} [  75.6599981] cache_lookup_linked() at netbsd:cache_lookup_linked+0x160
} [  75.6599981] namei_tryemulroot() at netbsd:namei_tryemulroot+0x298
} [  75.6599981] namei() at netbsd:namei+0x29
} [  75.6599981] vn_open() at netbsd:vn_open+0x8f
} [  75.6599981] do_open() at netbsd:do_open+0x119
} [  75.6599981] do_sys_openat() at netbsd:do_sys_openat+0x74
} [  75.6599981] sys_open() at netbsd:sys_open+0x24
} [  75.6599981] syscall() at netbsd:syscall+0x9c
} [  75.6599981] --- syscall (number 5) ---
} [  75.6599981] netbsd:syscall+0x9c:
} [  75.6599981] cpu0: End traceback...
} 
} 
} 3) server: EFI boot of Feb 6 2021, xenkernel413-4.13.3.tgz, serial console
} 
} On serial console, all that is seen is:
} 
} 2415648+1324000=0x3910ec         
} Loading /var/db/entropy-file
} Loading /netbsd-XEN3_DOM0
} Start @ 0xce600000 [1=0xce991000-0xce9910ec]... 
} Trampoline space cannot be allocated; will try fallback.
} 
} then it reboots
>-- End of excerpt from Patrick Welche