Re: pvgrub "Error 9: Unknown boot failure" booting Debian Jessie kernel (Was: Re: [PATCH v5 6/9] libxc: create unmapped initrd in domain builder if supported)

From: Juergen Gross <jgross@suse.com>
To: Ian Campbell <ian.campbell@citrix.com>, Wei Liu <wei.liu2@citrix.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	stefano.stabellini@eu.citrix.com, ian.jackson@eu.citrix.com,
	roger.pau@citrix.com, xen-devel@lists.xen.org
Subject: Re: pvgrub "Error 9: Unknown boot failure" booting Debian Jessie kernel (Was: Re: [PATCH v5 6/9] libxc: create unmapped initrd in domain builder if supported)
Date: Tue, 1 Dec 2015 08:15:53 +0100	[thread overview]
Message-ID: <565D4929.1090008@suse.com> (raw)
In-Reply-To: <1448902580.15768.54.camel@citrix.com>

On 30/11/15 17:56, Ian Campbell wrote:
> On Mon, 2015-11-30 at 16:25 +0000, Ian Campbell wrote:
>> (d54) Pinning the boot page table pfn 4be3 / mfn 1bfd71/1bfd71
>> (d54) pin_table: MFN 1bfd71
>> (XEN) mm.c:2417:d54v0 Bad type (saw 1400000000000001 != exp 7000000000000000) for mfn 165b81 (pfn 4d81)
> 
> I added a "BUG_ON(*pt_pfn == 0x4d81);" to mini-os's new_pt_frame, which
> after some messing with gdb to decode produced this stack trace:
> 
> 716e7: arch_do_exit + 9 in section .text
> 66176: do_exit + 28 in section .text
> 6ff68: new_pt_frame + 134 in section .text
> 70401: need_pgt + 410 in section .text
> 706ec: do_map_frames + 284 in section .text
> 66e72: sbrk + 130 in section .text
> 7768e: _sbrk_r + 30 in section .text
> 74fa3: _malloc_r + 1219 in section .text
> 76f3f: _realloc_r + 511 in section .text
> 31035: unsafe_flush + 46 in section .text
> 38bc7: unxz + 480 in section .text
> 310fa: xc_dom_decompress_unsafe + 110 in section .text
> 38cec: xc_try_xz_decode + 45 in section .text
> 286ff: xc_dom_probe_bzimage_kernel + 891 in section .text
> 24613: xc_dom_find_loader + 89 in section .text
> 24d83: xc_dom_parse_image + 58 in section .text
> 19d06: kexec + 1012 in section .text
> 03c27: pv_boot + 97 in section .text
> 08e4b: boot_func + 52 in section .text
> 0ab16: run_script + 294 in section .text
> 10848: run_menu + 3133 in section .text
> 10fb2: cmain + 1444 in section .text
> 04447: main + 303 in section .text
> 66991: call_main + 581 in section .text
> 03423: thread_starter + 9 in section .text
> 
> I'm not quite sure what to make of this, in particular I don't see anything
> in kexec.c which obviously looks after unmapping the heap or brk areas.

Nah, this backtrace shows a normal allocation path while
uncompressing the kernel image. I'd expect something like that.
Why shouldn't mini-os make use of pfn 4d81 somewhere?

I guess there is something wrong either in mini-os's memory
allocator (not very likely) or in kexec_allocate(). I'll try to
check those.

BTW: up to now I haven't managed to reproduce your problem. My
domains are just booting fine up to now. Is there a way I could
get the domain image which is failing? Maybe I could just try
to use that on my test machine with the same domain config you are
using.

Juergen