Re: DT case sensitivity

On Thu, Aug 23, 2018 at 11:29:01AM +1000, Benjamin Herrenschmidt wrote:

On Wed, 2018-08-22 at 20:26 -0500, Rob Herring wrote:

quoted

On Wed, Aug 22, 2018 at 8:14 PM Benjamin Herrenschmidt
[off-list ref] wrote:

quoted

On Wed, 2018-08-22 at 19:47 -0500, Rob Herring wrote:

quoted

The default DT string handling in the kernel is node names and
compatibles are case insensitive and property names are case sensitive
(Sparc is the the only variation and is opposite). It seems only PPC
(and perhaps only Power Macs?) needs to support case insensitive
comparisons. It was probably a mistake to follow PPC for new arches
and we should have made everything case sensitive from the start. So I
have a few questions for the DT historians. :)

Open Firmware itself is insensitive.

Doesn't it depend on the implementation? Otherwise, how is Sparc different?

Not sure ...

The standard requires case-sensitive.

Forth itself is insensitive for words

Not even.   http://forth.sourceforge.net/std/dpans/dpans3.htm#3.3.1.2

(Most non-ancient implementations are though).

but maybe not for string comparisons.

Only COMPARE is standardised, and that is case-sensitive comparison.  Many
systems have other words to do case-insensitive comparisons, or words where
some runtime flag determines the case-sensitivity.

Btw.  A node name in Open Firmware is generically
  driver-name@unit-address:device-arguments
where driver-name is the part that is in the "name" property; this whole
case-sensitivity business is even worse for FDT, where you also treat the
unit address as part of the name.  In real Open Firmware the address is
compared *as a number* (or as a few numbers), so it is naturally case-
insensitive (it does not care if you write 01a0 or 01A0, or 1a0 or 000001a0
etc.)


Segher