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Date: Fri, 18 Nov 2011 22:05:32 +0700
Message-ID: <CAA2qdGUf7muTUj_++SSVE-irBR6izGTv4GBXsdCihCc61yHL+w@mail.gmail.com>
Subject: Re: [gentoo-user] Re: Upgrading gcc: both 4.4 and 4.5 needed?
From: Pandu Poluan <pandu@poluan.info>
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On Nov 18, 2011 9:27 PM, "Willie Wong" <wwong@math.princeton.edu> wrote:
>
> On Thu, Nov 17, 2011 at 07:41:21PM +0000, James wrote:
> > > Now, why can't the USE descriptions be like the kernel option
> > > descriptions and have something like what Pandu wrote included?
> >
> > I added this to root's  .bashrc a long time ago:
> >
> > # USE flag settings hack by Ciaran McCreesh:
> > explainuseflag(){ sed -ne "s,^\([^ ]*:\)\?$1 - ,,p" $(portageq
> > portdir)/profiles/use.{,local.}desc; }
> > alias ef="explainuseflag"
> >
> >
> > Then simply use the alias for a quick check to learn about all the
different
> > uses of a given flag:
> >
> > 'ef graphite'
> >
> > # ef graphite
> > Enable support for non-Roman fonts via media-gfx/graphite2
> > Enable support for non-Roman fonts via media-gfx/graphite2
> > Add support for the framework for loop optimizations based on a
polyhedral
> > intermediate representation
> >
> > Then drill down into the a specific package's use flag meaning, using
the
> > aforementioned 'equery u' delineated by Albert.
>
> You people seem to miss my point. I know perfectly well how to find
> the USE descriptions. It is just that the USE description, in this
> case (as in many others) isn't terribly useful.
>
> "Add support for the framework for loop optimizations based on a
> polyhedral intermediate representation" means absolutely gibberish to
> me.
>
> But if one were to add an additional one or two lines a la Pandu,
> about how it is supposed to make " gcc-4.5.3 use a newer method to
> detect parallelism, thus (potentially) makes programs compiled by gcc
> to have better multithreaded performance" and perhaps even a Kernel
> help page style "It is mostly stable. If unsure, say Yes."
>
> It would be ever so much more helpful for people who would like to
> find out what new flags do before deciding whether or not to follow
> the default recommended by the devs which are set into the profile.
>
> (I'm not saying this type of hand holding is necessary for all flags:
> "enable support for non-Roman fonts via media-gfx/graphite2" is
> perfectly understandable, as are most other flags about features a
> "user" is likely to interact with. But for some of the more "system"
> type flags (see also that python/perl flag business from the recent
> months), I think the USE descriptions can stand some improvement.)
>

I agree with you (and not because my name is mentioned :-P).

I got lucky with USE "graphite": gcc's homepage is quite clear; a 15-minute
reading convinced me to try graphite. But there are still lots of other USE
flags that sent me on hours of goose-chase before I can enable/disable with
conviction.

I'm not sure where to put the more detailed explanations, though; perhaps a
$PN.usedesc file in the package's directory? Kind of a complement to the
.ebuild file(s).

Rgds,

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<p><br>
On Nov 18, 2011 9:27 PM, &quot;Willie Wong&quot; &lt;<a href=3D"mailto:wwon=
g@math.princeton.edu">wwong@math.princeton.edu</a>&gt; wrote:<br>
&gt;<br>
&gt; On Thu, Nov 17, 2011 at 07:41:21PM +0000, James wrote:<br>
&gt; &gt; &gt; Now, why can&#39;t the USE descriptions be like the kernel o=
ption<br>
&gt; &gt; &gt; descriptions and have something like what Pandu wrote includ=
ed?<br>
&gt; &gt;<br>
&gt; &gt; I added this to root&#39;s =C2=A0.bashrc a long time ago:<br>
&gt; &gt;<br>
&gt; &gt; # USE flag settings hack by Ciaran McCreesh:<br>
&gt; &gt; explainuseflag(){ sed -ne &quot;s,^\([^ ]*:\)\?$1 - ,,p&quot; $(p=
ortageq<br>
&gt; &gt; portdir)/profiles/use.{,local.}desc; }<br>
&gt; &gt; alias ef=3D&quot;explainuseflag&quot;<br>
&gt; &gt;<br>
&gt; &gt;<br>
&gt; &gt; Then simply use the alias for a quick check to learn about all th=
e different<br>
&gt; &gt; uses of a given flag:<br>
&gt; &gt;<br>
&gt; &gt; &#39;ef graphite&#39;<br>
&gt; &gt;<br>
&gt; &gt; # ef graphite<br>
&gt; &gt; Enable support for non-Roman fonts via media-gfx/graphite2<br>
&gt; &gt; Enable support for non-Roman fonts via media-gfx/graphite2<br>
&gt; &gt; Add support for the framework for loop optimizations based on a p=
olyhedral<br>
&gt; &gt; intermediate representation<br>
&gt; &gt;<br>
&gt; &gt; Then drill down into the a specific package&#39;s use flag meanin=
g, using the<br>
&gt; &gt; aforementioned &#39;equery u&#39; delineated by Albert.<br>
&gt;<br>
&gt; You people seem to miss my point. I know perfectly well how to find<br=
>
&gt; the USE descriptions. It is just that the USE description, in this<br>
&gt; case (as in many others) isn&#39;t terribly useful.<br>
&gt;<br>
&gt; &quot;Add support for the framework for loop optimizations based on a<=
br>
&gt; polyhedral intermediate representation&quot; means absolutely gibberis=
h to<br>
&gt; me.<br>
&gt;<br>
&gt; But if one were to add an additional one or two lines a la Pandu,<br>
&gt; about how it is supposed to make &quot; gcc-4.5.3 use a newer method t=
o<br>
&gt; detect parallelism, thus (potentially) makes programs compiled by gcc<=
br>
&gt; to have better multithreaded performance&quot; and perhaps even a Kern=
el<br>
&gt; help page style &quot;It is mostly stable. If unsure, say Yes.&quot;<b=
r>
&gt;<br>
&gt; It would be ever so much more helpful for people who would like to<br>
&gt; find out what new flags do before deciding whether or not to follow<br=
>
&gt; the default recommended by the devs which are set into the profile.<br=
>
&gt;<br>
&gt; (I&#39;m not saying this type of hand holding is necessary for all fla=
gs:<br>
&gt; &quot;enable support for non-Roman fonts via media-gfx/graphite2&quot;=
 is<br>
&gt; perfectly understandable, as are most other flags about features a<br>
&gt; &quot;user&quot; is likely to interact with. But for some of the more =
&quot;system&quot;<br>
&gt; type flags (see also that python/perl flag business from the recent<br=
>
&gt; months), I think the USE descriptions can stand some improvement.)<br>
&gt;</p>
<p>I agree with you (and not because my name is mentioned :-P).</p>
<p>I got lucky with USE &quot;graphite&quot;: gcc&#39;s homepage is quite c=
lear; a 15-minute reading convinced me to try graphite. But there are still=
 lots of other USE flags that sent me on hours of goose-chase before I can =
enable/disable with conviction.</p>

<p>I&#39;m not sure where to put the more detailed explanations, though; pe=
rhaps a $PN.usedesc file in the package&#39;s directory? Kind of a compleme=
nt to the .ebuild file(s).</p>
<p>Rgds,<br>
</p>

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