Re: [Xen-devel] kernel-ml-4.15.0-1.el7.elrepo.x86_64 doesn't boot as Xen PV domU

[Juergen Gross <jgross@xxxxxxxx>]

On 01/02/18 01:17, Michael Young wrote:
> On Wed, 31 Jan 2018, Michael Young wrote:
> 
>> (XEN) Guest stack trace from rsp=ffffffff82203e20:
>> (XEN)    0000000000000000 0000000000000000 0000000000000000
>> ffffffff81036a89
>> (XEN)    000000010000e030 0000000000010092 ffffffff82203e68
>> 000000000000e02b
>> (XEN)    0000000000000000 0000000000000000 0000000000000000
>> 0000000000000000
> 
> I have just spotted this is truncated. The full Guest stack trace is
> 
> (XEN) Guest stack trace from rsp=ffffffff82203e20:
> (XEN)    0000000000000000 0000000000000000 0000000000000000
> ffffffff81036a89
> (XEN)    000000010000e030 0000000000010092 ffffffff82203e68
> 000000000000e02b
> (XEN)    0000000000000000 0000000000000000 0000000000000000
> 0000000000000000
> (XEN)    ffffffff823777e0 0000000000000000 0000000000000000
> 0000000000000000
> (XEN)    0000000000000000 0000000000000000 ffffffff823777e0
> ffffffff82203f08
> (XEN)    ffffffff82203f0c ffffffff82203f04 ffffffff82203f00
> ffffffff82203f1c
> (XEN)    ffffffff81037673 ffffffff82203f10 ffffffff82203f14
> ffffffff82203f18
> (XEN)    0000000000003024 0000000000000000 0000000080000008
> 0000000000000000
> (XEN)    ffffffff81029d10 0000000000000000 0000000000000000
> 0000000000000000
> (XEN)    0000000000000000 0000000000000000 ffffffff82727b49
> 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000
> 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000
> 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000
> 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000
> 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000
> 0000000000000000
> (XEN)    0f00000060c0c748 ccccccccccccc305 cccccccccccccccc
> cccccccccccccccc
> (XEN)    cccccccccccccccc cccccccccccccccc cccccccccccccccc
> cccccccccccccccc
> (XEN)    cccccccccccccccc cccccccccccccccc cccccccccccccccc
> cccccccccccccccc
> (XEN)    cccccccccccccccc cccccccccccccccc cccccccccccccccc
> cccccccccccccccc
> (XEN)    cccccccccccccccc cccccccccccccccc cccccccccccccccc
> cccccccccccccccc
> 
> Some addresses from this that look like they might be relevant are
> 0xffffffff82203e20 <init_thread_union+15904>:    add    %al,(%rax)
> 0xffffffff81036a89 <init_scattered_cpuid_features+41>:
>     mov    %gs:0x28,%rax

Hmm, my compiler doesn't generate this instruction here. OTOH it does so
in many other functions, but those seem to be called only later.

Seems as if it would be a good idea to setup the GDT and %gs segment as
early as possible.

I'll have a try how far we can move the call of xen_setup_gdt() up in
the boot process.


Juergen

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