Re: [Xen-devel] IOMMU fault with IGD passthrough setup on XEN 4.8.0

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.01.17 at 11:49, <firemeteor@xxxxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, Jan 17, 2017 at 12:11 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
> 
>> >>> On 16.01.17 at 16:15, <firemeteor@xxxxxxxxxxxxxxxxxxxxx> wrote:
>> > On Mon, Jan 16, 2017 at 9:56 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>> >
>> >> For building a debug hypervisor, all you need to do is set
>> >> CONFIG_DEBUG=y in xen/.config. I don't think there are any
>> >> knobs to avoid log flooding - after all you've asked for the
>> >> verbosity via "iommu=verbose,debug".
>> >>
>> > I assume I do not need to redo the ./configure here.
>> > And I assume the xen/.config here refers to the root of the repos instead
>> > of the xen.git/xen subdirectory?
>>
>> I don't understand - I'd normally assume the two to be the same
>> (with just different context made visible).
>>
> I was trying to figure out if I followed your instruction properly.
> My first attempt only resulted in a binary with similar size with my
> previous one.
> Probably something went wrong.
> I put my source under /nas/src/xen, and I have a /nas/src/xen/.config file
> for the
> python layout knob according to the wiki.
> My first attempt put th CONFIG_DEBUG=y line in the same file.
> But now I suspect if I should use /nas/src/xen/xen/.config (note the double
> 'xen').

Yes indeed, that's the one. And you shouldn't add a new line, but
instead edit the existing one (with CONFIG_DEBUG commented out).

>> I couldn't find obvious debug knob in the gcc command-line, even though
>> the
>> > build is with -O1.
>>
>> Nor do I understand this remark.
>>
> I checked the GCC command-lines during build process with the .config
> change, with the expectation of something like -DDEBUG -g etc.
> But actually I saw none of them, only saw -O1.

The primary thing would be for -DNDEBUG to no longer be there (it
should be there for the non-debug build).

Jan


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