Re: [Xen-devel] MEM_SHARING_DEBUG

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Jun 14, 2016 at 01:46:45PM +0430, sepanta s wrote:
> On Tue, Jun 14, 2016 at 1:04 PM, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> 
> > On Tue, Jun 14, 2016 at 10:51:33AM +0430, sepanta s wrote:
> > > On Mon, Jun 13, 2016 at 12:59 PM, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> > >
> > > > On Sun, Jun 12, 2016 at 02:37:29PM +0430, sepanta s wrote:
> > > > > Hi,
> > > > >
> > > > > how to does MEM_SHARING_DEBUG works in xen ?
> > > > > This function is located at and its internal structure is
> > > > > xen/arch/x86/mm/mem_sharing.c
> > > > > <
> > > >
> > https://github.com/mirage/xen/blob/a6f2cdb633bf519244a16674031b8034b581ba7f/xen/arch/x86/mm/mem_sharing.c
> > > > >
> > > > > debugtrace_printk("*mem_sharing_debug*: %s(): " _f, __func__, ##_a)
> > > > > , so where the logs are being saved?
> > > >
> > > > From reading the code it can be configured to go to the hypervisor
> > > > console. You then can use xl dmesg to view it.
> > > >
> > > > Should I change the mem_debug_share to printk you mean?
> >
> > No. I think the output can go to console if you configure it properly.
> >
> > how can I configure it ?


Use "xl debug-keys h" and then "xl dmesg" to see all debug keys.

Try "xl debug-keys T" and then "xl dmesg"? I think you should be able to
see "debugtrace_printk now writing to $THING" where $THING would be
either buffer or console.

Note, you do need to enable DEBUG_TRACE_DUMP (a compile time option) in
your hypervisor to have debugtrace support.

> 
> 
> > You can change that to printk if you want to, but I don't think that's
> > absolutely necessary.
> >
> 
> > dmesg buffer is limited and I miss some debugging info.
> > >
> > >
> > > > Note that you need to have a debug hypervisor to have debugtrace
> > > > support. Then you can use xl debug-keys T to toggle whether the output
> > > > goes to console directly or goes to internal buffer.
> > > >
> > > >  I have enabled debugging in xen as I changed debug:= y in Config.mk.
> > > But after compilation and reboot, when I select booting from xen
> > hypervisor
> > > in the grub menu, my ubuntu goes beyond the initialzing ram and then it
> > > reboots.
> > > Am I missing something?
> > >
> >
> > I don't think it is related to MEM_SHARING_DEBUG.
> >
> > no it is not related to MEM_SHARING_DEBUG,
> I think it is because of compiling xen in debug mode.
> 

The only way to find out is to obtain relevant logs and see what goes
wrong.

http://wiki.xenproject.org/wiki/Xen_Serial_Console

Wei.

> > Wei.
> >
> > > Wei.
> > > >
> > > > > _______________________________________________
> > > > > Xen-devel mailing list
> > > > > Xen-devel@xxxxxxxxxxxxx
> > > > > http://lists.xen.org/xen-devel
> > > >
> > > >
> >
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@xxxxxxxxxxxxx
> > > http://lists.xen.org/xen-devel
> >
> >

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