Date: Sat, 21 Nov 2009 01:52:30 +0100 From: Polytropon <freebsd@edvax.de> To: "Ronald F. Guilmette" <rfg@tristatelogic.com> Cc: freebsd-questions@freebsd.org Subject: Re: BTX Loader crashes -- Help wanted Message-ID: <20091121015230.cf2c15dd.freebsd@edvax.de> In-Reply-To: <7972.1258760914@tristatelogic.com> References: <7872.1258759936@tristatelogic.com> <7972.1258760914@tristatelogic.com>
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On Fri, 20 Nov 2009 15:48:34 -0800, "Ronald F. Guilmette" <rfg@tristatelogic.com> wrote:
> But I have one question. The author sez to do this:
>
> dd if=8.0-BETA1-amd64-memstick.img of=/dev/da0 bs=10240 conv=sync
>
> I just want to know what the effect of conv=sync and why it might be
> necessary.
According to "man dd":
bs=n Set both input and output block size to n bytes, superseding the
ibs and obs operands. If no conversion values other than
noerror, notrunc or sync are specified, then each input block is
copied to the output as a single block without any aggregation
of short blocks.
in conjunction with
conv=value[,value ...]
Where value is one of the symbols from the following list.
sync Pad every input block to the input buffer size. Spaces
are used for pad bytes if a block oriented conversion
value is specified, otherwise NUL bytes are used.
it appears that the data is ensured to be "properly
aligned" with a possibly different block size on the
source or target media. As far as I remember, not
giving the bs= argument would result in a default
block size of 512 bytes which may - but don't ask
me why - lead to a non-functioning target USB stick.
--
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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