From owner-freebsd-hackers@freebsd.org Wed Nov 22 07:08:16 2017 Return-Path: Delivered-To: freebsd-hackers@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 E2C11DE2DD8 for ; Wed, 22 Nov 2017 07:08:16 +0000 (UTC) (envelope-from khanzf@gmail.com) Received: from mail-qt0-x236.google.com (mail-qt0-x236.google.com [IPv6:2607:f8b0:400d:c0d::236]) (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 9A1FB6FF3F for ; Wed, 22 Nov 2017 07:08:16 +0000 (UTC) (envelope-from khanzf@gmail.com) Received: by mail-qt0-x236.google.com with SMTP id p44so22514014qtj.6 for ; Tue, 21 Nov 2017 23:08:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:from:subject:message-id:date:user-agent:mime-version :content-language:content-transfer-encoding; bh=7dODCZNJL9Z0LeEKGJ9Ymvvb4X39NDJBb2GRL5FRQP4=; b=l140mJ5ISVt+OTKjcHt55tWhLynGDCohSq5ql62H8u0m4hBvbVk6aRYVr2paZMsK+n EsnnNUuud+HxXcqyRZW+pofE8eYwdzxlHyzFSvSJAZosAN8kXQojX+dJYOFm9JNOiaq7 z8p46KHSS0nSKoR9+JH9GICgFD4EP9hIia/9tMd+mIhjNPKi9I0x0v9GUNRr1b88UMmK C6hCl6ComY65Z+f4mvoEaV80saCytyeTGWL0iCIBdK1N162Vc2cyJdXa1whv7K8oHzWk FvTK6VYPlYDfjaiIEEHnCe2GNzS8A8L8tyZq7PfePef961Y7EwD1EdOMbhzfCkNJ6thw FQ9g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:from:subject:message-id:date:user-agent :mime-version:content-language:content-transfer-encoding; bh=7dODCZNJL9Z0LeEKGJ9Ymvvb4X39NDJBb2GRL5FRQP4=; b=SCAyxsH2sQY90djdtV66BBx8K5yWUQfAEAlQqDJD81Sqwx8Gc5F9EMwqfSuXVBKOiK omK1KGcq9sckZPRKvPS0fdP28+za8bFzp2SqiTIF6MZOrqMSXRN5dO6MdYyURG0cWnxz 3qrabvv/mJgyjryPyqgYFnknWa1F2jXJTS5PpZpPL8p/1qDlpX1/BfqJLfQRqDjJTqx0 CIrco2pX8DhmPTmZDECNEk1zblsFRkyQtIQfny6lQjvWFy32TlvUwtdfZguR2bQl0kMC 41KutYUx37U4LvkRPE4z5wwaEyPnK1X3uYK7M3ycPL6p/PIGqeW0G0PmOYGwZn6vbuF3 b2Gg== X-Gm-Message-State: AJaThX7EhJgztD+hNJ4G+8x9vO7EkU0IO28K9EKTWRYA+KIAzzJK5Tt0 Hdnbke/XdC9JKxTq/Y+Ao4KsPLxD X-Google-Smtp-Source: AGs4zMZS3sNDtKPZ/+GCcMeM3hwhhPnFstL3+xVidsQ2/pQk/OubGzD1O9DM6KfUGba5tCDCMvJoTg== X-Received: by 10.200.42.14 with SMTP id k14mr30495809qtk.20.1511334495634; Tue, 21 Nov 2017 23:08:15 -0800 (PST) Received: from pc.farhan.codes ([2001:470:8:209::dead:c0de]) by smtp.gmail.com with ESMTPSA id t12sm10345763qkl.41.2017.11.21.23.08.15 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 Nov 2017 23:08:15 -0800 (PST) To: freebsd-hackers@freebsd.org From: Farhan Khan Subject: Is ddb(4) over a USB-to-Serial port possible? Message-ID: <11ce9826-f768-3ea0-547d-2d182d1552f0@gmail.com> Date: Wed, 22 Nov 2017 02:08:14 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Nov 2017 07:08:17 -0000 Hi all I am reading here in section "10.5, On-Line Kernel Debugging User Remote GDB" that you can run ddb(4) over a serial cable. I am interested in setting this up. My development box does not have a serial port (however, I do see a uart0 device in the kernel messages), so I attached a USB serial port attached to a machine with a serial port. The device uses the uslcom(4) driver and is listed as "Silicon Labs CP2102 USB to UART Bridge Controller". When I enter ddb and enter "gdb" I receive the error "The remote GDB backend could not be selected." The hint.uart.0.port in /boot/device.hints is still set to 0x3F8, which corresponds to the aforementioned kernel messages. I am not certain if this is the same port as the USB-based serial port. Does this feature work over USB? Thanks, Farhan Khan