From owner-freebsd-hackers@freebsd.org Sat Apr 20 18:29:23 2019 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 5CF271572482 for ; Sat, 20 Apr 2019 18:29:23 +0000 (UTC) (envelope-from ian@freebsd.org) Received: from outbound2m.ore.mailhop.org (outbound2m.ore.mailhop.org [54.149.155.156]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 996726D542 for ; Sat, 20 Apr 2019 18:29:22 +0000 (UTC) (envelope-from ian@freebsd.org) ARC-Seal: i=1; a=rsa-sha256; t=1555784960; cv=none; d=outbound.mailhop.org; s=arc-outbound20181012; b=IRdS7QHtw/TFPV2QEqSqxVqFuGTE0tQiJvUtczHpfEkDbWQqxl+7JMyudBMEdQfE3yGjBuuIJmYx5 YHZwZOsk+4d2cuPgPnwTa+jFcC30ef8ZGBTXA8u1DgDrK71M5hg1eMMNwwZWZnD2ZHciBWwzwwrZVs 9ZpNTCw2IBbHsSRnx3FvtFxOODlPolOFJh5ouyxoYwSInChwzXG8i4VjxnJSvOX//nYeLJ/jBiDICo 5XRuLcCNlls8rw4r5EpNJe4Jw5T3mLVmNnVLPU2mZetFmjihvMwCtKf4m6J2PfQ+DgnKM2bnyI5QPv kZbZ0VESH1CkN7DKz4DHPoN0J8AFSvw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=outbound.mailhop.org; s=arc-outbound20181012; h=content-transfer-encoding:mime-version:content-type:references:in-reply-to: date:cc:to:from:subject:message-id:dkim-signature:from; bh=gLU3nWse0Pt1BgfSf+7f9OpTmRSluhjsobMODa7Q9Ng=; b=qWJPUxpIn/0nRXAyPkhdLWBAUo3VJ5p5RIcoKG3SKGJnIL6+jO/bODA6hXaRbEcr+9HqAIepEjmhL Xq9bl8W3JDdnyQy6rSNaHapyi74+eY3a36bnheLrvrJE8hLAEJdL/Vju46nSfKLAYBin4PzDspz9M1 kH2a4Vu6Cy06xWoLtlfcwkqXyLHLcwWpnVHaSHLpbB0cC9p8AIlZ0PNH80nRXbEUTkFI6L5xj4A2jq w1v7muzEVQW/TLKs/UF1/EloetvfAZK2LB8Gw6Cz4zrKbn6yO4J12eS/jphvNOyaCEXcp9Ocx7zLnx Al7ZRkJ6JSHVYjLKx7QurxlZKmQf/1A== ARC-Authentication-Results: i=1; outbound4.ore.mailhop.org; spf=softfail smtp.mailfrom=freebsd.org smtp.remote-ip=67.177.211.60; dmarc=none header.from=freebsd.org; arc=none header.oldest-pass=0; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=outbound.mailhop.org; s=dkim-high; h=content-transfer-encoding:mime-version:content-type:references:in-reply-to: date:cc:to:from:subject:message-id:from; bh=gLU3nWse0Pt1BgfSf+7f9OpTmRSluhjsobMODa7Q9Ng=; b=rTCur1bTHiWWBYQEdb5+g9dL+Pxl06CX+GFAShZ57U78uRq8p2PC75aZ5BTgrpgJ+dlB5LNmQp6Xz 4jhzR78LEQOrWwdPfWbRVUS1M4wkWlRIuVe5gYfm0/QyuKu1XW/f+MOu4Lgvr+6Kr32crpfEH/+N2L 8EQVyVcbQyyZl5kM/ZZN/f7fbJMGYJSc2As5HVEHjKTS73XQ48N+reGIuFj/XT9BdrV9NCRUX274Gw hMop6wCjQ4FHsfBQPgcHitvuRqhe3ItyB6DCgB+lcIykjRKLOshIAgfgUll5S0zkmy7y8HPNwkQWR/ bjG/VRypbuYNMYwZkcWf8P/yvUTRLbw== X-MHO-RoutePath: aGlwcGll X-MHO-User: 34e99285-639a-11e9-919f-112c64a8cf29 X-Report-Abuse-To: https://support.duocircle.com/support/solutions/articles/5000540958-duocircle-standard-smtp-abuse-information X-Originating-IP: 67.177.211.60 X-Mail-Handler: DuoCircle Outbound SMTP Received: from ilsoft.org (unknown [67.177.211.60]) by outbound4.ore.mailhop.org (Halon) with ESMTPSA id 34e99285-639a-11e9-919f-112c64a8cf29; Sat, 20 Apr 2019 18:29:19 +0000 (UTC) Received: from rev (rev [172.22.42.240]) by ilsoft.org (8.15.2/8.15.2) with ESMTP id x3KITHOK057815; Sat, 20 Apr 2019 12:29:17 -0600 (MDT) (envelope-from ian@freebsd.org) Message-ID: Subject: Re: bhyve VM stopped to boot after moving virtio disks From: Ian Lepore To: Igor Mozolevsky Cc: Hackers freeBSD Date: Sat, 20 Apr 2019 12:29:17 -0600 In-Reply-To: References: <2006ff8da153bbe5e7f620da9260ee1518bd248f.camel@freebsd.org> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 FreeBSD GNOME Team Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 996726D542 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.98 / 15.00]; local_wl_from(0.00)[freebsd.org]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; NEURAL_HAM_SHORT(-0.98)[-0.978,0]; ASN(0.00)[asn:16509, ipnet:54.148.0.0/15, country:US] X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 20 Apr 2019 18:29:23 -0000 On Sat, 2019-04-20 at 18:45 +0100, Igor Mozolevsky wrote: > On Sat, 20 Apr 2019 at 18:00, Ian Lepore wrote: > > > > dd absolutely will fail to copy the last block of the source if it > > isn't exactly the blocksize and you didn't specify conv=sync, and > > it > > will return a zero status when doing so. It appears you've > > convinced > > yourself otherwise, but for anyone else reading this thread, be > > aware: > > conv=sync is required to copy the last part of the source if it's > > smaller than the blocksize. > > > Isn't that contrary to the POSIX Spec? Reading the manual [1], it is > implied (from STDERR part of the main section) that dd will read and > write partial blocks, cf. truncated blocks?.. > > 1. https://pubs.opengroup.org/onlinepubs/9699919799/utilities/dd.html > > Damn, why do people trim away the entire useful context of an email thread when replying? I almost don't want to reply to this because at this point all the useful info is gone. In any case, in retrospect, what I said was wrong. Using conv=sync is important when the output is a device that has fixed block sizes where you cannot write a partial block. When the destination is a file where short writes work correctly, it will copy the entire source correctly. -- Ian