Add "--mem-usage" support for s390x

[Michael Holzheu]

On Mon, 29 Sep 2014 17:04:32 +0800
Baoquan He <bhe at redhat.com> wrote:

> On 09/26/14 at 01:34pm, Michael Holzheu wrote:
> > On Fri, 26 Sep 2014 16:55:46 +0800
> 
> > > > Isn't this a chicken-and-egg problem? In order to determine vmalloc start
> > > > I have to be able to read memory. But in order to read memory I have
> > > > to call get_kcore_dump_loads() first.
> > > > 
> > > > What about using /proc/iomem to find out if an address is a real address?
> > > 
> > > Well, that's good it works for s390. Anyway in get_kcore_dump_loads() it
> > > just gets the physical ram region, and filter out the unwanted region,
> > > so your method is good. In x86_64, the is_vmalloc_addr_x86_64 is not
> > > only filtering the vmalloc, but vmmemmap and modules_vaadr region. For
> > > simplicity it's only named as is_vmalloc_addr.
> > 
> > Not sure if I understood, why ths is_real_addr() function does not
> > work for x86_64.
> > 
> > Also for x86 all three areas, vmalloc, vmemmap, and modules_vaddr, are
> > virtual memory regions with addresses outside of the the memory ranges
> > where /proc/iommem reports physical memory, right?
> > 
> > So the new is_real_addr() function should return false for that areas.
> 
> is_real_addr() should work for x86_64, this almost does the way
> kexec-tools is doing. Originally I just consider this for x86_64,
> skipped other ARCHs. From x86_64 point of view, processing kcore only
> need to pick up the program segments we want. If it's hard to handle it,
> I am fine with it that you use the is_real_addr to do it. But please
> don't use this name, it could be is_phy_addr() or somthing like that.
> Please post your patch and test x86_64 too and we can review it.
> 
> In fact the other way is wrapping your is_real_addr() to
> is_vmalloc_addr_s390(), and make it work for s390. If later other ARCH
> also has this requirements, raise it to be common function. Anyway it's
> fine to me if it can work.

Hi Baoquan,

Because I don't have the possibility to test on x86_64 I decided to
make a s390x only patch. I will send it with the next note.

Thanks for your help!
Michael