Re: [Xen-devel] libxl: cannot start guest

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2012-05-21 at 14:10 +0100, Christoph Egger wrote:
> On 05/21/12 14:15, Ian Campbell wrote:
> 
> > On Mon, 2012-05-21 at 11:26 +0100, Christoph Egger wrote:
> >> On 05/18/12 17:58, Ian Campbell wrote:
> >>
> >>>
> >>>> In libxl__build_post() I check the return value
> >>>> of libxl__sched_set_params().
> >>>
> >>> The mesages about scheduler params are a known and benign issue.
> >>>
> >>>> Now trying to start a guest results in this failure:
> >>>>
> >>>> xc: info: VIRTUAL MEMORY ARRANGEMENT:
> >>>>   Loader:        0000000000100000->000000000019bd04
> >>>>   TOTAL:         0000000000000000->00000000ff800000
> >>>>   ENTRY ADDRESS: 0000000000100000
> >>>> xc: info: PHYSICAL MEMORY ALLOCATION:
> >>>>   4KB PAGES: 0x0000000000000200
> >>>>   2MB PAGES: 0x00000000000003fb
> >>>>   1GB PAGES: 0x0000000000000002
> >>>> libxl: error: libxl.c:3211:libxl_sched_credit_domain_set: Cpu weight out
> >>>> of range, valid values are within range from 1 to 65535
> >>>> libxl: error: libxl_create.c:694:domcreate_bootloader_done: cannot
> >>>> (re-)build domain: -6
> >>>> libxl: error: libxl_dm.c:1104:libxl__destroy_device_model: Couldn't find
> >>>> device model's pid: No such file or directory
> >>>
> >>> Is your device model dying for some reason? Anything
> >>> in /var/log/xen/*guest*.log about it?
> >>
> >>
> >> The guest logfile doesn't exist.
> > 
> > Sorry, I meant guest as in $GUEST_NAME rather than literally "guest" (I
> > was totally non-obvious about that, sorry!).
> 
> 
> I understood it that way. The guest logfile doesn't exist.
> 
> > 
> >> Does that mean the errors happens before device model has been started at 
> >> all?
> > 
> > I think/hope if that were the case you would get messages about failure
> > to exec etc rather than timeouts.
> > 
> >>>
> >>> You could try "xl -vvv cr ..." too, not sure what it will say.
> >>
> >>
> >> libxl: debug: libxl_device.c:183:libxl__device_disk_set_backend: Disk
> >> vdev=hda spec.backend=unknown
> >> libxl: debug: libxl_device.c:219:libxl__device_disk_set_backend: Disk
> >> vdev=hda, using backend phy
> >> xc: detail: elf_parse_binary: phdr: paddr=0x100000 memsz=0x9bd04
> >> xc: detail: elf_parse_binary: memory: 0x100000 -> 0x19bd04
> >> xc: info: VIRTUAL MEMORY ARRANGEMENT:
> >>   Loader:        0000000000100000->000000000019bd04
> >>   TOTAL:         0000000000000000->00000000ff800000
> >>   ENTRY ADDRESS: 0000000000100000
> >> xc: info: PHYSICAL MEMORY ALLOCATION:
> >>   4KB PAGES: 0x0000000000000200
> >>   2MB PAGES: 0x00000000000003fb
> >>   1GB PAGES: 0x0000000000000002
> > 
> > No messages about "xs transaction failed: Bad file descriptor" any more?
> > 
> >> xc: detail: elf_load_binary: phdr 0 at 0x0x7f7ff7f42000 -> 0x0x7f7ff7fd4b74
> >> libxl: error: libxl.c:3211:libxl_sched_credit_domain_set: Cpu weight out
> >> of range, valid values are within range from 1 to 65535
> >> libxl: error: libxl_create.c:694:domcreate_bootloader_done: cannot
> >> (re-)build domain: -6
> >> libxl: error: libxl_dm.c:1104:libxl__destroy_device_model: Couldn't find
> >> device model's pid: No such file or directory
> >> libxl: error: libxl.c:1162:libxl_domain_destroy:
> >> libxl__destroy_device_model failed for 2
> > 
> > Hrm, actually, the device model stuff might be a red-herring -- that's
> > trying to tear down the device model on failure and it is entirely
> > reasonable for the device model to not be running if we didn't get as
> > far as starting it...
> > 
> > The interesting message is just:
> >> libxl: error: libxl_create.c:694:domcreate_bootloader_done: cannot
> >> (re-)build domain: -6
> > 
> > Which is unhelpfully just a general failure from libxl__domain_build.
> > 
> > It seems that we have a non-logging failure path in there somewhere. I'm
> > afraid that the easieist way to fix this is probably just to dive into
> > libxl__domain_build and add prints on the various error cases of sub
> > functions, then recurse as you identify which one is failing etc..
> 
> I did that:
> 
> Parsing config from /root/hvm-guest/netbsd_64b.conf
> libxl: debug: libxl_device.c:183:libxl__device_disk_set_backend: Disk
> vdev=hda spec.backend=unknown
> libxl: debug: libxl_device.c:219:libxl__device_disk_set_backend: Disk
> vdev=hda, using backend phy
> xc: detail: elf_parse_binary: phdr: paddr=0x100000 memsz=0x9bd04
> xc: detail: elf_parse_binary: memory: 0x100000 -> 0x19bd04
> xc: info: VIRTUAL MEMORY ARRANGEMENT:
>   Loader:        0000000000100000->000000000019bd04
>   TOTAL:         0000000000000000->00000000ff800000
>   ENTRY ADDRESS: 0000000000100000
> xc: info: PHYSICAL MEMORY ALLOCATION:
>   4KB PAGES: 0x0000000000000200
>   2MB PAGES: 0x00000000000003fb
>   1GB PAGES: 0x0000000000000002
> xc: detail: elf_load_binary: phdr 0 at 0x0x7f7ff7f42000 -> 0x0x7f7ff7fd4b74
> libxl: error: libxl.c:3213:libxl_sched_credit_domain_set: Cpu weight out
> of range, valid values are within range from 1 to 65535
> libxl: error: libxl_dom.c:74:libxl__sched_set_params:
> libxl_sched_credit_domain_set failed -6
> libxl: error: libxl_dom.c:192:libxl__build_post: libxl__sched_set_params
> failed -6
> libxl: error: libxl_create.c:322:libxl__domain_build: libxl__build_post
> failed: -6
> libxl: error: libxl_create.c:709:domcreate_bootloader_done: cannot
> (re-)build domain: -6
> libxl: error: libxl_dm.c:1104:libxl__destroy_device_model: Couldn't find
> device model's pid: No such file or directory
> libxl: error: libxl.c:1162:libxl_domain_destroy:
> libxl__destroy_device_model failed for 6
> xc: debug: hypercall buffer: total allocations:1264 total releases:1264
> xc: debug: hypercall buffer: current allocations:0 maximum allocations:2
> xc: debug: hypercall buffer: cache current size:2
> xc: debug: hypercall buffer: cache hits:1261 misses:2 toobig:1
> libxl: error: libxl.c:155:libxl_ctx_free: libxl_ctx_free: call
> xs_daemon_close
> 
> 
> So it is indeed that ERROR_INVAL from that 'benign' error

In my version of libxl libxl__build_post doesn't even look at the return
value of libxl__sched_set_params.
    ....
    libxl__sched_set_params (gc, domid, &(info->sched_params));
    ....

the only other exit path from that function is:
    dom_path = libxl__xs_get_dompath(gc, domid);
    if (!dom_path) {
        return ERROR_FAIL;
    }
which is consistent with the original errors you had (but if ERROR_FAIL,
not ERROR_INVAL). This doesn't really help me figure out what is going
on though :-/

Ian.


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