From owner-freebsd-usb@freebsd.org Sun Dec 1 10:28:08 2019 Return-Path: Delivered-To: freebsd-usb@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 41CC61C65A2 for ; Sun, 1 Dec 2019 10:28:08 +0000 (UTC) (envelope-from gljennjohn@gmail.com) Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 47QkwQ5Z1tz4gGK for ; Sun, 1 Dec 2019 10:28:06 +0000 (UTC) (envelope-from gljennjohn@gmail.com) Received: by mail-wr1-x444.google.com with SMTP id b18so40471797wrj.8 for ; Sun, 01 Dec 2019 02:28:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:subject:message-id:in-reply-to:references:reply-to :mime-version:content-transfer-encoding; bh=hmuutWjfccnG7a8QjMukKcV0hTGzONCfI1CAX2yiVbg=; b=CZhMHUGrZQlVhMEY9uyut15yv0oS5mJDnvoqmOe5RBoY7CRyum68r2gQRbfWJ9360q XZFaywcFVhUQm/6sHdcKw+b9jWc7ZxiiQXMMJdcA2S/hytLhIe8U7VGWjarzCzH4+TuP 3ttHIP0RJQtzwRg4lZe754ZJ2bcK74TGfSPVakIv+p9fLOkeCkgwWAh5QDcsmie4vpNr /8pp/EqAj0IB5N6/SppsHd7yT0KBmRb7jeFMty4DPia7196VJ1k2U1/PSZfI2D7bWzo8 fF0vkLKF4UNjkPklarKyDKdDwd6WeByoSLQCOtBaoR1CHtps8Jd9m5SykYH1Q3jbT0FC 1jGQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:subject:message-id:in-reply-to :references:reply-to:mime-version:content-transfer-encoding; bh=hmuutWjfccnG7a8QjMukKcV0hTGzONCfI1CAX2yiVbg=; b=WBIp3yaqRgFZbryaxx7nhMvGVlUP8VRhV2Fkw/oOgTXvW7kQaaKoTdBgCkEc4j7uvF 20B9Y/88yrDXKdvPnfM2rHPxcWQrcm7ZNj8LmwIZFhMYMogSu8bPIz9x35ce7ywHTSY+ OG61P/1eVgdmtCsAr18Yy3641h752nqsHp+Ds/zNkjWp49E6YPRsnhwRI1+ebH8tQVsG kAc0SIDPnTutg78zdAkicBpufnAcbbRzsfuSb2PvEcNsM0PYLVJLSU9sTkv0nxPRt0h7 TVxzG+rysmMMa4Rpaos6m+LoQ7//tK6Vmd/pdahefeWpZFEVz6HhyrhIrpLO6+Joj5Z7 nelg== X-Gm-Message-State: APjAAAVWIpQIEAgyyr9t7wKtSp+UXXS1RgdBrG6t78U1Q7WH6pYB09Gz yLNppS9asMgWHl8oCCDf2birWuos X-Google-Smtp-Source: APXvYqxmSSbmnKm8Fmr4V2Sb02/7+YYTuv6Yuh9ANIfqijiPy73krvNz4JHBx7+RcFOARr/YnjAvhQ== X-Received: by 2002:a5d:5306:: with SMTP id e6mr62433960wrv.187.1575196084540; Sun, 01 Dec 2019 02:28:04 -0800 (PST) Received: from ernst.home (pD9E239E8.dip0.t-ipconnect.de. [217.226.57.232]) by smtp.gmail.com with ESMTPSA id u69sm21073247wmu.39.2019.12.01.02.28.03 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 01 Dec 2019 02:28:04 -0800 (PST) Date: Sun, 1 Dec 2019 11:28:03 +0100 From: Gary Jennejohn To: freebsd-usb@freebsd.org Subject: Re: pendrive clone impossible ? Message-ID: <20191201112803.7c7677d4@ernst.home> In-Reply-To: <20191201131416.3a1554ec@asd2> References: <20191130223322.1028feab.freebsd@edvax.de> <20191130234900.81464b43.freebsd@edvax.de> <20191201050341.4a02879a@asd2> <20191201082801.6a8c7639@ernst.home> <20191201131416.3a1554ec@asd2> Reply-To: gljennjohn@gmail.com X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; amd64-portbld-freebsd13.0) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 47QkwQ5Z1tz4gGK X-Spamd-Bar: - Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=CZhMHUGr; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of gljennjohn@gmail.com designates 2a00:1450:4864:20::444 as permitted sender) smtp.mailfrom=gljennjohn@gmail.com X-Spamd-Result: default: False [-2.00 / 15.00]; RCVD_VIA_SMTP_AUTH(0.00)[]; HAS_REPLYTO(0.00)[gljennjohn@gmail.com]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36]; FREEMAIL_FROM(0.00)[gmail.com]; TO_DN_NONE(0.00)[]; REPLYTO_ADDR_EQ_FROM(0.00)[]; RCVD_COUNT_THREE(0.00)[3]; DKIM_TRACE(0.00)[gmail.com:+]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; FROM_EQ_ENVFROM(0.00)[]; SUBJECT_ENDS_QUESTION(1.00)[]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; MIME_TRACE(0.00)[0:+]; DWL_DNSWL_NONE(0.00)[gmail.com.dwl.dnswl.org : 127.0.5.0]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-0.998,0]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; RECEIVED_SPAMHAUS_PBL(0.00)[232.57.226.217.khpj7ygk5idzvmvt5x4ziurxhy.zen.dq.spamhaus.net : 127.0.0.10]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-usb@freebsd.org]; FREEMAIL_REPLYTO(0.00)[gmail.com]; IP_SCORE_FREEMAIL(0.00)[]; RCPT_COUNT_ONE(0.00)[1]; IP_SCORE(0.00)[ip: (3.01), ipnet: 2a00:1450::/32(-2.69), asn: 15169(-1.94), country: US(-0.05)]; RCVD_IN_DNSWL_NONE(0.00)[4.4.4.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.5.4.1.0.0.a.2.list.dnswl.org : 127.0.5.0]; RCVD_TLS_ALL(0.00)[] X-BeenThere: freebsd-usb@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FreeBSD support for USB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 Dec 2019 10:28:08 -0000 On Sun, 1 Dec 2019 13:14:16 +0300 Anatoly wrote: > On Sun, 1 Dec 2019 08:28:01 +0100 > Gary Jennejohn wrote: > > > The geom code protects certain parts of the data area on the > > drive, in particular GPT/MBR areas, unless ``sysctl > > kern.geom.debugflags=16'' is run beforehand. One can see this in > > many places in the geom code. > > > > I always set this sysctl when I know I'm going to overwrite the > > first sectors of a drive. > > > Interesting, but I've succefully overwrited MBR many times > on FreeBSD 5.x-11.x without setting this sysctl. > I've learned about this sysctl when I first time failed to overwrite bsd > label inside MBR slice under FreeBSD 7.1 with dd (but not MBR). There > was explicit write error, not just silent succeful write to nowhere. I > may be wrong, but as I remember, I newer got this trouble again > starting from 10.x. > Is there something new on 12.x? > This sysctl has been around for quite some time. I added a shellscript to my ~/bin to set it in 2015. IIRC Julian Elischer requested it because he had problems initializing disks. I just use it by default when I write to the first sectors on a disk. There is geom code which explicitly checks whether debugflags is set to 16. I have not looked at the code to see what happens when that is the case. -- Gary Jennejohn