Subject: [PATCH v2] ARM: remove name from machine_desc for DT platforms

From: [email-masked] (Rob Herring)
Date: Thu, 14 Nov 2013 08:46:14 -0600

On 11/14/2013 07:33 AM, Grant Likely wrote:
> On Thu, Nov 14, 2013 at 9:32 PM, Arnd Bergmann <[email-masked]> wrote:
>> On Wednesday 13 November 2013, Rob Herring wrote:
>>> I'm not inclined to expand cpuinfo and prior attempts to add more info
>>> to cpuinfo like SoC name have failed. The differences between x86 and
>>> arm cpuinfo already cause issues for arm. lscpu does not really work on arm.
>>
>> Well, they turned into drivers/base/soc.c, which adds the information in
>> a structured way in sysfs, but is only used on a couple of platforms.
>>
>>> I'd actually prefer If you really want more system info, then go read
>>> /proc/device-tree.
> 
> I really don't mind pulling that information out of /proc/cpuinfo. My
> point is merely that it is incredibly useful to be able to easily find
> out exactly which machine_desc got chosen on any given platform. I
> don't think I should have to grep the source tree to figure that out.
> 
> The kernel log is useful, but it is also helpful to have it in a /proc
> or /sysfs file for when the kernel log overflows. /proc/device-tree
> doesn't give that information.

Either we want to shrink/remove machine_desc or we don't. If we do, then
the name has to go at some point. So what is the reason to remove it
later rather than sooner? Later means we will have "Generic DT based
system" in cpuinfo as platforms transition. Perhaps that is useful to
know in the short term, but once all platforms print the same thing the
information becomes useless. Then we either remove Hardware field from
cpuinfo or change to use DT info. That's changing the string twice
rather than once.

We probably have at least a dozen machine_desc's we are close to being
able to remove (sunxi, picoxcell, highbank, dove, rockchip, virt,
several sh-mobile). There's also more that probably can be combined
together which will change the string in /proc/cpuinfo.

If this is a required feature then we should make machine_desc common
(or at least part of it) with the other arches that have copied arm and
then add it to arm64 as well. Then I could do further consolidation of
the FDT machine matching code. Otherwise this is all just pointless
architecture variation that really has nothing to do with the architecture.

Rob