public inbox for
 help / color / mirror / Atom feed
From: "Joseph S. Myers" <>
To: <>
Cc: <>, <>,
	"Ryan S. Arnold"	<>
Subject: Re: e500 port: getcontext / setcontext / swapcontext
Date: Wed, 18 Sep 2013 19:33:00 -0000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Wed, 18 Sep 2013, Steven Munroe wrote:

> Joseph I must really question the wisdom of merging the e500 into the
> same source with the "classical" PPC32 code. 
> The unified GPR/FPR set of the e500 impacts the ABI in many different
> ways from the classic PPC32 soft-float or hard-float that I fear this
> will be a constant source of misunderstanding and error in the future.
> I am much more comfortable keeping the e500 specific codes in different
> source files and different parts of the tree.

The design is detailed at 
<>.  The 
function-calling ABI is identical to soft-float (the only case in which 
register high parts are used in argument passing / return is for 
e500-specific vector types).  With this port version, the other aspects of 
the glibc ABI also match soft-float, so soft-float binaries can run with 
glibc built for e500; this avoids an unnecessary proliferation of ABI 
variants (requiring their own ABI test baselines etc.).  The present 
getcontext / setcontext / swapcontext patch follows the same approach as 
the support in those functions for other optional features, with a macro 
__CONTEXT_ENABLE_E500 conditioning the e500-specific code, and in fact the 
substance of the e500 implementation is in a separate file context-e500.h 
in this case because that was the natural way to avoid code duplication in 
the swapcontext sources.

Joseph S. Myers

  reply	other threads:[~2013-09-18 19:33 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-18 17:29 Joseph S. Myers
2013-09-18 18:25 ` Steven Munroe
2013-09-18 19:33   ` Joseph S. Myers [this message]
2013-09-19 15:52 ` Ryan S. Arnold
2013-09-26 15:39   ` Joseph S. Myers

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:

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

  git send-email \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).