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Date:      Wed, 23 Sep 2015 18:04:31 +0200
From:      Arrigo Marchiori <ardovm@yahoo.it>
To:        FreeBSD Embedded list <freebsd-embedded@freebsd.org>
Subject:   [NanoBSD] Double copy when using swap as backing?
Message-ID:  <20150923160431.GB37383@nuvolo>

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Hello list,

I was looking at the nanobsd.sh script from 10-STABLE and I found
something that I could not understand.

In function create_diskimage(), lines 639-650 result in two
invocations of dd:

 1- if NANO_IMAGE_MBRONLY is `yes':
    dd if=/dev/${MD} of=${NANO_DISKIMGDIR}/_.disk.mbr bs=512 count=1
    dd conv=sparse if=/dev/${MD} of=${IMG} bs=64k

 2- otherwise:
    dd if=/dev/${MD} of=${IMG} bs=64k
    dd conv=sparse if=/dev/${MD} of=${IMG} bs=64k

Case 2 looks a duplicate to me; the first dd could be avoided. Or did
I miss anything?

I don't use swap-backed md's therefore I cannot experiment with that
part. I just wonder if it may help someone by speeding their builds
up.

Best regards,
-- 
rigo

http://rigo.altervista.org



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