Re: [PATCH v1] memory-hotplug.rst: complete admin-guide overhaul

[David Hildenbrand]

Looks like a was too fast with my resend ;)

> > > > -Phases of memory hotplug
> > > > +Further, the basic memory hot(un)plug infrastructure in Linux is nowadays
> > > > +also used to expose PMEM, other performance-differentiated
> > >
> > >                         ^ persistent memory (PMEM)
>
> Just in case you've missed this one ^ ;-)

I did catch that :)

[...]

> > "If it fails, an error will be returned by the kernel via the systemcall
> > that triggered modifying of the respective file."
>
> I also think that write(2) to /sys/devices/system/memory/memoryXXX/online
> will fail.  But the inner workings of system call, its return value and the
> ERRNO are probably not very interesting to a person that did
>
> echo 0 > /sys/devices/system/memory/memoryXXX/online
>
> Maybe something like
>
>    If it fails, the state of the memory block will remain unchanged and the
>    above command will fail.

Thanks, I'll use that.

> And maybe an example of how echo reports some unrelated error message :)
>
> > > > +Observing the State of Memory Blocks
>
> ...
>
> > > > -Now, a boot option for making a memory block which consists of migratable pages
> > > > -is supported. By specifying "kernelcore=" or "movablecore=" boot option, you can
> > > > -create ZONE_MOVABLE...a zone which is just used for movable pages.
> > > > -(See also Documentation/admin-guide/kernel-parameters.rst)
> > > > +		    For online memory blocks, ``DMA``, ``DMA32``, ``Normal``,
> > > > +		    ``Movable`` and ``none`` may be returned. ``none`` indicates
> > >
> > > Highmem? Or we don't support hotplug on 32 bits?
> >
> > We only support 64 bit:
> >
> > config MEMORY_HOTPLUG
> > 	...
> > 	depends on 64BIT || BROKEN
> >
> > Worth a comment in the document "Introduction":
> >
> > "Linux only supports memory hot(un)plug on selected 64 bit architectures,
> > such as x86_64, aarch64, ppc64, s390x and ia64."
>   
>                   ^ arm64 ?

I think aarch64 is historically actually the right(tm) thing to use in 
general ... but nowadays it doesn't matter anymore. It's "arch/arm64" 
... the inconsistency is real. (interesting read: 
https://stackoverflow.com/questions/31851611/differences-between-arm64-and-aarch64)

But it's the same mess as using x86 vs. x86_64 vs. x64 vs. AMD64 for the 
64 bit extension of IA-32.

So I'll convert that to arm64.

--
Thanks,

David / dhildenb