From owner-freebsd-arch@freebsd.org Wed Jul 20 20:39:58 2016 Return-Path: Delivered-To: freebsd-arch@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id DFBE3B9FDAC for ; Wed, 20 Jul 2016 20:39:58 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mail-pa0-x22c.google.com (mail-pa0-x22c.google.com [IPv6:2607:f8b0:400e:c03::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id B92A712B7 for ; Wed, 20 Jul 2016 20:39:58 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mail-pa0-x22c.google.com with SMTP id ks6so21560692pab.0 for ; Wed, 20 Jul 2016 13:39:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=tFz+5gAXT7BkGFEUoedvCu/toykDDeQoeAX4wzCuUQM=; b=B2C00QNkPwaeXhg1DkhzEqdREan1bIN/GAnOUf9Z53ZlOND47k1mPaHmCoJdj+7UbE aA4gKrVTaRjAu2XBgiHPdtgAj4kk3mwDvLLbgrNR5QECEiRfRfEkVXihC2PdMrmc35Tl 33BZk3Kp8ZkBnmAxHAahVie9ezbqCSmBcZTcbb0taxqrTAiXA03zgkr5+lI3nk0nyysf 0L+BBRTFsKMFUP7/ogqjh3G32KTIPkSQdnzr+Kp22v0jVR2NVLsNWx9KD39Y0vkmVPbR UCfUWugSmXzeE2P7Ub/QvMtuPex81LyXNNvqL28BuE0A3wYD0YeMjn5Os3cT8KU8U/C/ pp/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=tFz+5gAXT7BkGFEUoedvCu/toykDDeQoeAX4wzCuUQM=; b=LYeJzxpcqKDPZHX2Xb1uQ/AWsU56VGgxuMvkJy8TVrAS1cVee2AmPfGmQ6xl2bJsgu IOUSYHaaSGc/FTrKcPpAdhmPQrBwPPent2H3obaaMwV7gzkCo/RIxzxke4Fip+k7QEXF 9LLol6sN9Nd+oO6j+WTfkYWlYvJTKKrO7VlwjzqJnAC2OZ/K/iRHoz2fyRx9jg9xCRik KethxA/3DcszwFR0N0thAPaPzuRA0tYzd647nzAkWd8CZvq5y8Z5qiUwb5dhZoNlA96X 7wv9cZn4dEZ3XB09GmGcuzx0TsozR/HUOLg0Cpz1D08I16vlA8vnVknglQH+JTV+22qP JZxw== X-Gm-Message-State: ALyK8tLqvuSHS1OrceIoztfE2HIQxF6mwLpAIkDEct8+B8Qx1w5vLa6YUNT2aYwYUm70TQ== X-Received: by 10.66.25.171 with SMTP id d11mr77393820pag.3.1469047198076; Wed, 20 Jul 2016 13:39:58 -0700 (PDT) Received: from [100.127.70.152] ([69.53.245.200]) by smtp.gmail.com with ESMTPSA id f3sm6642011pff.26.2016.07.20.13.39.57 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 20 Jul 2016 13:39:57 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: Retiring in-tree GDB From: Warner Losh In-Reply-To: <3871457.xzmrTRH8AM@ralph.baldwin.cx> Date: Wed, 20 Jul 2016 14:39:55 -0600 Cc: freebsd-arch@freebsd.org, Sean Bruno Content-Transfer-Encoding: quoted-printable Message-Id: References: <2678091.es0AGJQ0Ou@ralph.baldwin.cx> <4450836.nX37FfBzNy@ralph.baldwin.cx> <068a0167-1d5d-a437-60e7-b74e407060a2@freebsd.org> <3871457.xzmrTRH8AM@ralph.baldwin.cx> To: John Baldwin X-Mailer: Apple Mail (2.3124) X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 20 Jul 2016 20:39:59 -0000 > On Jul 20, 2016, at 2:19 PM, John Baldwin wrote: >=20 > On Wednesday, July 20, 2016 01:20:34 PM Sean Bruno wrote: >>=20 >> On 07/20/16 13:00, John Baldwin wrote: >>> On Tuesday, October 20, 2015 01:36:28 PM John Baldwin wrote: >>>> When this topic was last raised (by Warner I believe), the primary = objection >>>> (certainly my main one) was that the in-tree kgdb was the only = kernel debugger >>>> available. kgdb is now available via the devel/gdb port in ports = (and as of >>>> last week was enabled by default, so 'pkg install gdb' will get you = a kgdb >>>> binary). The kgdb in ports is in general superior to the one in = the base >>>> system. It is a cross debugger by default (and with my pending = patches to >>>> libkvm it even supports cross debugging of vmcores). >>>>=20 >>>> There are some issues still with devel/gdb: namely it does not = currently >>>> support some of the platforms supported by our in tree gdb such as = arm and >>>> mips. For these platforms I think the in-tree gdb will need to = remain until >>>> there is a suitable alternative. >>>>=20 >>>> However, I would like to propose that we retire the in-tree GDB for = some of >>>> our platforms (namely x86) for 11. In particular, I think we = should default >>>> to enabling lldb and disabling gdb for platforms that meet the = following >>>> criteria: >>>>=20 >>>> 1) devel/gdb works including thread and kgdb support >>>> 2) lldb works >>>>=20 >>>> We could perhaps be more aggressive and handle lldb and gdb toggles >>>> independently, but I think we want to ship some sort of userland = debugger >>>> out of the box on all of our platforms. The question I think might = be if >>>> we end up with platforms where 1) is true but 2) is not (such as = powerpc). >>>>=20 >>>> I believe that these conditions are only true for x86 currently. >>>>=20 >>>> Comments? >>>=20 >>> I believe I've fixed the one last thing that was depending on = /usr/bin/gdb >>> (crashinfo) to use devel/gdb if it is present. I'd either like to = disable >>> the base gdb on amd64 in the next week or so on HEAD, or perhaps if = people are >>> really gutsy, disable it for all platforms on HEAD. We still don't = have kgdb >>> in ports for non-x86 (though for ppc at least kgdb in ports and base = is >>> equally dysfunctional). >>>=20 >>> However, to start with: >>>=20 >>> 1) Does anyone have a reason to keep /usr/bin/gdb on amd64? >>>=20 >>> 2) Does anyone have a reason to keep /usr/bin/gdb on !amd64? >>>=20 >>=20 >> I don't have an immediate use case in the mips/mips64 case. Should >> ports "just work" here or do I need some kind of "cross gdb"? >=20 > ports gdb does not yet work on mips. Once it supports mips it will = work as > both a native and cross debugger, but it just doesn't know about = FreeBSD/mips > at all. Does /usr/bin/gdb work on mips? It does, kinda. there=E2=80=99s a lot of stuff it gets right, so it can = be useful. However, there=E2=80=99s enough wrong that it=E2=80=99s super frustrating. So = there=E2=80=99s a low bar to replacement. If I can build a new /bin/cat and debug it with a ports = gdb, even if things are broken that kinda work now, I=E2=80=99m all for = replacement. If /usr/bin/gdb were super duper cool on mips, I=E2=80=99d have a = different take, but gdb on mips has never been stellar. Warner=