From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=unavailable autolearn_force=no version=3.4.4 X-Received: by 10.224.205.138 with SMTP id fq10mr413739qab.1.1372813305015; Tue, 02 Jul 2013 18:01:45 -0700 (PDT) X-Received: by 10.50.4.99 with SMTP id j3mr1195089igj.6.1372813304972; Tue, 02 Jul 2013 18:01:44 -0700 (PDT) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!mx05.eternal-september.org!feeder.eternal-september.org!usenet.blueworldhosting.com!feeder01.blueworldhosting.com!npeer01.iad.highwinds-media.com!news.highwinds-media.com!feed-me.highwinds-media.com!y2no180489qax.0!news-out.google.com!f7ni623qai.0!nntp.google.com!y2no180482qax.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Tue, 2 Jul 2013 18:01:44 -0700 (PDT) In-Reply-To: Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=108.90.156.221; posting-account=qZVz2QoAAAAN9WxYp-9jYb7jORc4Zqwt NNTP-Posting-Host: 108.90.156.221 References: <31f9819e-6509-4d67-acea-4d2ba9a96c04@googlegroups.com> <4csim6j63mk4.1c54vo5v7eu8c.dlg@40tude.net> <51d280e7$0$6556$9b4e6d93@newsspool4.arcor-online.net> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: Subject: Re: Help with embedded hardware/software platform selection for ADA From: mjsilva@scriptoriumdesigns.com Injection-Date: Wed, 03 Jul 2013 01:01:45 +0000 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Received-Bytes: 3746 Xref: news.eternal-september.org comp.lang.ada:16070 Date: 2013-07-02T18:01:44-07:00 List-Id: On Tuesday, July 2, 2013 3:47:17 PM UTC-7, Randy Brukardt wrote: > wrote in message=20 >=20 > news:d39ad66d-63a3-43e8-a8ae-3c799c12512e@googlegroups.com... >=20 > ... >=20 > >> Why a hobbyist would even look at Ravenscar? >=20 > >> >=20 > >Because it provides the simple multitasking that a great many projects c= an=20 >=20 > >benefit from. >=20 >=20 >=20 > That's true only if you think hobbyists want a lot a frustration. That's= =20 >=20 > because Ravenscar makes it impossible to build resilient systems - the la= ck=20 >=20 > of a entry call with timeout means that any error or failure will cause a= =20 >=20 > deadlock. If you are going to use fancy proof tools to *prove* that there= =20 >=20 > are no errors or deadlock possibilities, then this is OK (and that's what= =20 >=20 > Ravenscar is for), but hobbyists are unlikely to have access to such tool= s.=20 >=20 > (Heck, *I* have no access to such tools - I'm not even sure if they reall= y=20 >=20 > exist.) >=20 >=20 >=20 > Even if you don't have a sensible recovery action, the timeout can raise = an=20 >=20 > exception pinpointing where the deadlock happened -- which greatly eases= =20 >=20 > debugging. (I don't think Claw would have been usable without that, as it= is=20 >=20 > way too easy to unintentially cause a deadlock by doing the wrong thing i= n=20 >=20 > an action handler.) >=20 >=20 >=20 > So, IMHO (and much like SPARK), Ravenscar is a tool needed only in very= =20 >=20 > specialized circumstances (typically, some sort of certification=20 >=20 > requirement). Otherwise, one ought to forget about it and use Ada as it w= as=20 >=20 > intended. Interesting point. I understood the "why Ravenscar" to mean "why any taski= ng, even if limited?" which may have been a misunderstanding on my part. O= f course I'd like to get as much Ada tasking on bare metal as possible, but= I'd willing to give up having the whole package to get something useable t= hat will fit on smaller hardware. I'd be willing to settle for some taskin= g sweet spot as regards code size vs tasking features. That was the point = of my reply.