Re: [PATCH 2/2] ACPICA: support Generic Address Structure bit_offset in acpi_read/write

[Thomas Renninger <trenn@suse.de>]

On Thursday 17 November 2011 21:27:40 Rafael J. Wysocki wrote:
> On Thursday, November 17, 2011, Huang Ying wrote:
... 
> > page_is_ram() is used by x86 ioremap implementation to exclude RAM
> > range.  So I think it can be used here.
> 
> Except that ACPI is not going to be x86-specific any more in the (near?)
> future.  Have you taken that into consideration?
This is about the NVS ram resource registering/requesting problem?
I had an idea to make the resource management more fine grained.
There already is a possibility to pass "flags" to request_mem_region macro:
include/linux/ioport.h:
#define __request_mem_region(start,n,name, excl) __request_region(&iomem_resource, (start), (n), (name), excl)
#define request_muxed_region(start,n,name)    __request_region(&ioport_resource, (start), (n), (name), IORESOURCE_MUXED)
...


The idea is to e.g. flag memory with:
  MEM_NVS
  MEM_RESERVED
  (MEM_PCI?)
  other archs may have other memory flags
  ...
once it got detected/initialized at early boot.

and then have something like:
request_specific_mem_region(start, n, name, (MEM_NVS | MEM_RESERVED))
for apei (or others allowed to access NVS mem) which is only successful
if the requested memory region has been marked as NVS/RESERVED memory.

This is nothing I have time for right now, therefore don't get
the mail wrong: I don't object to adding any other working solution
discussed here.
Just an idea how this could be solved in a cleaner way,
also re-usable for others.

What do you think?

       Thomas