Re: [PATCH 1/2 v2] kdump: add the vmcoreinfo documentation

[Dave Young <dyoung@redhat.com>]

> >> +init_uts_ns
> >> +===========
> >> +This is the UTS namespace, which is used to isolate two specific elements
> >> +of the system that relate to the uname system call. The UTS namespace is
> >> +named after the data structure used to store information returned by the
> >> +uname system call.
> > 
> > Those non-obvious exports should also have a short explanation why
> > they're part of VMCOREINFO.
> > 
> >> +
> >> +node_online_map
> >> +===============
> >> +It is a macro definition, actually it is an arrary node_states[N_ONLINE],
> >> +and it represents the set of online node in a system, one bit position
> >> +per node number.
> > 
> > Ditto.
> > 
> > So yeah, people can find out what those things are but I think it is
> > more important to state here *why* they're part of VMCOREINFO and how
> > they're used and why they're exported.
> > 
> 
> This is a good question.
> 
> For these two *why*, it should be easy to understand. Because user-space tools
> need to know basic information, such as the symbol values, field offset, structure
> size, etc. Otherwise, these tools won't know how to analyze the memory of the crash
> kernel.
> 
> For the second question 'how they are used', we can get the answer from user-space
> tools, such as makedumpfile, crash tools. Therefore, it may not need to explain any
> more in kernel document. On the other hand, if we must put these contents into kernel
> document, i have to say, that would be a hard task.

It should be a good chance to learn how makedumpfile works :),  Maybe it is
hard to get *all* of them, but it would be good to dig and find the
thing you can find then explain it.  And leave those *unknown* part as
FIXME or TODO, people can add description later. 

Added Kazu in cc as well..

Thanks
Dave