Re: [Xen-devel] [xen-unstable test] 64494: regressions - FAIL

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 20/11/15 15:41, Andrew Cooper wrote:
> On 20/11/15 15:34, Wei Liu wrote:
>> On Fri, Nov 20, 2015 at 04:29:04PM +0100, Juergen Gross wrote:
>>> On 20/11/15 16:14, Jan Beulich wrote:
>>>>>>> On 19.11.15 at 12:47, <JGross@xxxxxxxx> wrote:
>>>>> On 19/11/15 11:30, Ian Campbell wrote:
>>>>>> On Thu, 2015-11-19 at 11:24 +0100, Juergen Gross wrote:
>>>>>>> On 18/11/15 15:49, Wei Liu wrote:
>>>>>>>> Hi Juergen
>>>>>>>>
>>>>>>>> Looks like there is something we missed after all.
>>>>>>>>
>>>>>>>> On Wed, Nov 18, 2015 at 02:31:57PM +0000, osstest service owner wrote:
>>>>>>>>> flight 64494 xen-unstable real [real]
>>>>>>>>> http://logs.test-lab.xenproject.org/osstest/logs/64494/ 
>>>>>>>>>
>>>>>>>>> Regressions :-(
>>>>>>>>>
>>>>>>>>> Tests which did not succeed and are blocking,
>>>>>>>>> including tests which could not be run:
>>>>>>>>>  test-amd64-amd64-i386-pvgrub 10 guest-start               fail REGR.
>>>>>>>>> vs. 64035
>>>>>>>> Nov 18 05:11:19.753014 (d2) Bootstrapping...
>>>>>>>> Nov 18 05:11:19.769108 (d2) Xen Minimal OS!
>>>>>>>> Nov 18 05:11:19.769134 (d2)   start_info: 0xa13000(VA)
>>>>>>>> Nov 18 05:11:19.769158 (d2)     nr_pages: 0x20000
>>>>>>>> Nov 18 05:11:19.777046 (d2)   shared_inf: 0xca1fc000(MA)
>>>>>>>> Nov 18 05:11:19.777072 (d2)      pt_base: 0xa16000(VA)
>>>>>>>> Nov 18 05:11:19.785042 (d2) nr_pt_frames: 0xb
>>>>>>>> Nov 18 05:11:19.785077 (d2)     mfn_list: 0x993000(VA)
>>>>>>>> Nov 18 05:11:19.785108 (d2)    mod_start: 0x0(VA)
>>>>>>>> Nov 18 05:11:19.785135 (d2)      mod_len: 0
>>>>>>>> Nov 18 05:11:19.793047 (d2)        flags: 0x0
>>>>>>>> Nov 18 05:11:19.793077 (d2)     cmd_line: (hd0,0)/boot/grub/menu.lst
>>>>>>>> Nov 18 05:11:19.793108 (d2)        stack: 0x972580-0x992580
>>>>>>>> Nov 18 05:11:19.801150 (d2) MM: Init
>>>>>>>> Nov 18 05:11:19.801181 (d2)       _text: 0x0(VA)
>>>>>>>> Nov 18 05:11:19.801197 (d2)      _etext: 0x7b22d(VA)
>>>>>>>> Nov 18 05:11:19.809104 (d2)    _erodata: 0xa4000(VA)
>>>>>>>> Nov 18 05:11:19.809123 (d2)      _edata: 0xa81a8(VA)
>>>>>>>> Nov 18 05:11:19.809138 (d2) stack start: 0x972580(VA)
>>>>>>>> Nov 18 05:11:19.817062 (d2)        _end: 0x992b30(VA)
>>>>>>>> Nov 18 05:11:19.817099 (d2)   start_pfn: a24
>>>>>>>> Nov 18 05:11:19.817125 (d2)     max_pfn: 20000
>>>>>>>> Nov 18 05:11:19.825037 (d2) Mapping memory range 0x1000000 - 0x20000000
>>>>>>>> Nov 18 05:11:19.825071 (d2) setting 0x0-0xa4000 readonly
>>>>>>>> Nov 18 05:11:19.825100 (d2) skipped 1000
>>>>>>>> Nov 18 05:11:19.833049 (d2) MM: Initialise page allocator for
>>>>>>>> b1c000(b1c000)-20000000(20000000)
>>>>>>>> Nov 18 05:11:19.833089 (d2) Page fault at linear address c00008, eip
>>>>>>>> 5fc70, regs 0x98ff28, sp b1c000, our_sp 0x98fefc, code 2
>>>>>>>> Nov 18 05:11:19.849044 (d2) Page fault in pagetable walk (access to
>>>>>>>> invalid memory?).
>>>>>>>>
>>>>>>>> The pvgrub in used is 32 bit. 64 bit (which I myself tested) seemed to
>>>>>>>> be working fine.
>>>>>>> Okay, I'm hitting this issue, too. I'll investigate further.
>>>>>> Do we want to revert $something in the meantime? If so, what...
>>>>>>
>>>>> The problem is really located in pvgrub:
>>>> One question I have here: Even if this gets fixed in pvgrub (or
>>>> mini-os, as it now seems), can we tolerate all existing mini-os
>>>> clones now being broken on -unstable (and hence then also
>>>> eventually on 4.7)?
>>> It would be rather inconvenient if not. The problem is mini-os is
>>> relying on an interface which was never meant to be this way. grub-xen
>>> is already breaking this interface today, and I think this is okay.
>>>
>>> Is mini-os shipped independent of Xen in any other product or stand
>>> alone?
>> Rump kernel has quite a bit of code based on mini-os. I will take care
>> of that. That's the only "real" thing based on mini-os that I'm aware
>> of.
>>
>> Given that we split mini-os out just last release, I don't expect there
>> are many clones in the wild.
> Mirage microkernels use a mini-os base as well.
>
> Having said that, I don't think we should not block this change because
> mini-os has been broken in a dumb way for ages.
>
> People using mini-os based things will have to take a "stable update" of
> their mini-os to run on Xen 4.7 when it is release.  Linux is treated
> exactly the same with bugs like this.

Apologies - too many negatives.  "I don't think we should block this
change".

~Andrew

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