public inbox for linuxppc-dev@ozlabs.org 
 help / color / mirror / Atom feed

From: Jon Loeliger <jdl@jdl•com>
To: David Gibson <david@gibson•dropbear.id.au>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: dtc: RFC: Fix some lexical problems with references
Date: Mon, 26 Nov 2007 16:38:20 -0600	[thread overview]
Message-ID: <E1Iwmaq-0002n8-U0@jdl.com> (raw)
In-Reply-To: Your message of "Thu, 22 Nov 2007 17:10:07 +1100." <20071122061007.GA22888@localhost.localdomain>

So, like, the other day David Gibson mumbled:
> The recent change to the lexer to only recognize property and node
> names in the appropriate context removed a number of lexical warts in
> our language that would have gotten ugly as we add expression support
> and so forth.
> 
> But there's one nasty one remaining: references can contain a full
> path, including the various problematic node name characters (',', '+'
> and '-', for example).  This would cause trouble with expressions, and
> it also causes trouble with the patch I'm working on to allow
> expanding references to paths rather than phandles.  This patch
> therefore reworks the lexer to mitigate these problems.
> 
> 	- References to labels cause no problems.  These are now
> recognized separately from references to full paths.  No syntax change
> here.
> 
> 	- References to full paths, including problematic characters
> are allowed by "quoting" the path with braces
> e.g. &{/pci@10000/somedevice@3,8000}.  The braces protect any internal
> problematic characters from being confused with operators or whatever.
> 
> 	- For compatibility with existing dts files, in v0 dts files
> we allow bare references to paths as before &/foo/bar/whatever - but
> *only* if the path contains no troublesome characters.  Specifically
> only [a-zA-Z0-9_@/] are allowed.
> 
> This is an incompatible change to the dts-v1 format, but since AFAIK
> no-one has yet switched to dts-v1 files, I think we can get away with
> it.  Better to make the transition when people to convert to v1, and
> get rid of the problematic old syntax.
> 
> Strictly speaking, it's also an incompatible change to the v0 format,
> since some path references that were allowed before are no longer
> allowed.  I suspect no-one has been using the no-longer-supported
> forms (certainly none of the kernel dts files will cause trouble).  We
> might need to think about this harder, though.

This all sounds fine by me.  We should take the incompatibility hit
once here and now; it shouldn't be a problem to eek in some more still.

Thanks,
jdl

next prev parent reply	other threads:[~2007-11-26 22:38 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-11-22  6:10 dtc: RFC: Fix some lexical problems with references David Gibson
2007-11-22  6:23 ` David Gibson
2007-11-26 22:38 ` Jon Loeliger [this message]
2007-11-28 19:53 ` Jon Loeliger
2007-12-05 22:34 ` Josh Boyer
2007-12-05 22:44   ` Josh Boyer

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=E1Iwmaq-0002n8-U0@jdl.com \
    --to=jdl@jdl$(echo .)com \
    --cc=david@gibson$(echo .)dropbear.id.au \
    --cc=linuxppc-dev@ozlabs$(echo .)org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox