Supporting cross-debugging vmcores in libkvm

[John Baldwin]

On Friday, August 28, 2015 02:19:52 PM John-Mark Gurney wrote:
> John Baldwin wrote this message on Fri, Aug 28, 2015 at 13:39 -0700:
> > On Friday, August 28, 2015 11:27:05 AM John-Mark Gurney wrote:
> > > John Baldwin wrote this message on Tue, Aug 04, 2015 at 10:56 -0700:
> > > How will we prevent native only aware apps from getting confused when
> > > accessing non-native cores?  Will kvm_openfiles fail for non-native
> > > cores? or will kvm_read fail for non-native cores?
> > 
> > kvm_openfiles() will fail.  kvm_open2() will fail for a non-native core
> > if a symbol resolving routine is not supplied.
> > 
> > One API question I had is if it would be useful to allow a void * cookie
> > to be passed to the symbol resolving routine (the same cookie would be
> > passed to kvm_open2() and stored internally to be passed on each resolution
> > request).  I think in practice we don't need that level of complexity
> > though (my kgdb changes did not).
> 
> I can't think of a reason it would be required, but that doesn't mean
> someone else wouldn't need it...

You need to resolve symbols to find the root of the global page table
structures that let you do virtual to physical translations.

> Though wouldn't the core parser provide the symbol lookup function?
> 
> > I will need to rebase this to port the arm64 minidump support over, but
> > I also need people to test this.
> 
> I'll see what I can do to help test it...

Mostly it needs testing on non-x86.

-- 
John Baldwin