From owner-freebsd-mips@FreeBSD.ORG Wed Feb 19 19:50:18 2014 Return-Path: Delivered-To: freebsd-mips@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 801DA4DC for ; Wed, 19 Feb 2014 19:50:18 +0000 (UTC) Received: from mail-lb0-f171.google.com (mail-lb0-f171.google.com [209.85.217.171]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 026FE1CCA for ; Wed, 19 Feb 2014 19:50:17 +0000 (UTC) Received: by mail-lb0-f171.google.com with SMTP id c11so647748lbj.2 for ; Wed, 19 Feb 2014 11:50:16 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc:content-type; bh=tVU2xWRUx3YP6rBw6AKj55wjVxRBBKD4YGevN7sE+9s=; b=j8VGJxy2sEM24lPy+D1xa1rLEErY+jtAhNs8N5V7XG4+Z35AsDr5eAX3tWlCFuIQkD fmRDqfl1ar9bqTmCT0jcoJfoXHrUMCRx/CK/DiXKLi0Ce5f1c2a+b2VicIAARwqBzRrX QdWA16CHQc+kyZM+aqGKebRWyeA9dm1ERfO9XEc9BPGO5Ja4PkaeEb4MKbe0a/Slc5i8 0rItncchaErqgxyGqeLDa1gQiZXxlajn8ITurx4rlagGBRuuSy13cD7oSHtoji7pCbYm TeCwJPMExR7UpA0TLn2ydIxEKiQHmpqLx1HabHFDsGmVhbqKij2bz2hVMw2qINfkn2nZ IlcA== X-Gm-Message-State: ALoCoQkuAbSsfSPk8vXvT2iOQdB9dkkM3xnhb9+DfIo6LHwJC6cJwI5fFeVd8kknzYGAuY1sdGNX X-Received: by 10.112.154.202 with SMTP id vq10mr25929586lbb.3.1392839415899; Wed, 19 Feb 2014 11:50:15 -0800 (PST) MIME-Version: 1.0 Sender: juli@clockworksquid.com Received: by 10.152.134.146 with HTTP; Wed, 19 Feb 2014 11:49:55 -0800 (PST) In-Reply-To: References: From: Juli Mallett Date: Wed, 19 Feb 2014 11:49:55 -0800 X-Google-Sender-Auth: bXFd1_mD7xDZop3fEhO88T8hfME Message-ID: Subject: Re: [RFC] 16K page size for kernel thread stack (patch) To: Stacey Son Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.17 Cc: "freebsd-mips@freebsd.org" X-BeenThere: freebsd-mips@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Porting FreeBSD to MIPS List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 Feb 2014 19:50:18 -0000 On Wed, Feb 19, 2014 at 11:41 AM, Stacey Son wrote: > > On Feb 18, 2014, at 7:58 PM, Adrian Chadd wrote: > > I don't think the mips24k/mips74k cores I have support ULRI. > > I am starting to wonder which mips CPUs actually do have an ULRI. > Basically-none. Some sources I've read from when the rdhwr approach was first implemented clearly thought it would pretty much never be implemented in hardware, and certainly most implementations after it became widespread didn't implement it, and its use only became common in the recent past. Until we started using it for TLS, GXemul would exit rather than trap on the rdhwr. I don't believe I've ever possessed a piece of hardware which actually implements the register itself, and there's actually a huge disincentive to do so because a lot of software has been written now which assumes that rdhwr will always trap and be implemented in software, and so won't set up the actual hardware register with the right value, breaking existing software. Juli.