Date: Sun, 23 Oct 2011 17:54:28 -0400 From: Arnaud Lacombe <lacombar@gmail.com> To: "Andrey V. Elsukov" <bu7cher@yandex.ru> Cc: Warren Block <wblock@wonkity.com>, Garrett Cooper <yanegomi@gmail.com>, Glen Barber <gjb@freebsd.org>, Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-current@freebsd.org, Benjamin Kaduk <kaduk@mit.edu> Subject: Re: aliasing (or renaming) kern.geom.debugflags Message-ID: <CACqU3MXr-JoAd=q%2BobUiSOkQG03Kq4jEs6g%2BvkJ5V99i23713g@mail.gmail.com> In-Reply-To: <4E8F5D47.9070904@yandex.ru> References: <81477.1318015137@critter.freebsd.dk> <4E8F55CC.3060302@FreeBSD.org> <4E8F5D47.9070904@yandex.ru>
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Hi, 2011/10/7 Andrey V. Elsukov <bu7cher@yandex.ru>: > On 07.10.2011 23:41, Glen Barber wrote: >> In my experience, without kern.geom.debugflags=16, the MBR will not be >> written to the memstick, leaving you with what would effectively be a >> coaster in the not-so-distant past. > > The problem is that this bad suggestion is everywhere in the Internet. > And users use it always even when it not needed. I think it is bad idea > add it in the our official documentation. FWIW, boot0cfg(8) also mentions it: NOTE Protection mechanisms in the geom(4) subsystem might prevent boot0cfg from being able to update the MBR on a mounted disk. Instructions for temporarily disabling these protection mechanisms can be found in the geom(4) manpage. Specifically, do a sysctl kern.geom.debugflags=0x10 to allow writing to the MBR, and restore it to 0 afterwards. - Arnaud > When you doing all in the right way using debugflags=16 is not needed. > And it is really dangerous when you doing something what you do not know > exactly. > > -- > WBR, Andrey V. Elsukov > >
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