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Re: [PATCH] qemu-nbd: Removed deprecated --partition option


From: Max Reitz
Subject: Re: [PATCH] qemu-nbd: Removed deprecated --partition option
Date: Thu, 23 Jan 2020 13:10:31 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1

On 22.01.20 22:43, Eric Blake wrote:
> The option was deprecated in 4.0.0 (commit 0ae2d546); it's now been
> long enough with no complaints to follow through with that process.
> 
> Signed-off-by: Eric Blake <address@hidden>
> ---
>  qemu-deprecated.texi |  49 ++++++----------
>  qemu-nbd.c           | 133 +------------------------------------------
>  qemu-nbd.texi        |  13 ++---
>  3 files changed, 24 insertions(+), 171 deletions(-)
> 
> diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
> index 8471eef9c22d..1b4c638db8e0 100644
> --- a/qemu-deprecated.texi
> +++ b/qemu-deprecated.texi
> @@ -304,37 +304,6 @@ The above, converted to the current supported format:
> 
>  @section Related binaries
> 
> -@subsection qemu-nbd --partition (since 4.0.0)
> -
> -The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
> -can only handle MBR partitions, and has never correctly handled
> -logical partitions beyond partition 5.  If you know the offset and
> -length of the partition (perhaps by using @code{sfdisk} within the
> -guest), you can achieve the effect of exporting just that subset of
> -the disk by use of the @option{--image-opts} option with a raw
> -blockdev using the @code{offset} and @code{size} parameters layered on
> -top of any other existing blockdev. For example, if partition 1 is
> -100MiB long starting at 1MiB, the old command:
> -
> -@code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
> -
> -can be rewritten as:
> -
> -@code{qemu-nbd -t --image-opts 
> driver=raw,offset=1M,size=100M,file.driver=qcow2,file.backing.driver=file,file.backing.filename=file.qcow2}
> -
> -Alternatively, the @code{nbdkit} project provides a more powerful
> -partition filter on top of its nbd plugin, which can be used to select
> -an arbitrary MBR or GPT partition on top of any other full-image NBD
> -export.  Using this to rewrite the above example results in:
> -
> -@code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &}
> -@code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1}
> -
> -Note that if you are exposing the export via /dev/nbd0, it is easier
> -to just export the entire image and then mount only /dev/nbd0p1 than
> -it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
> -subset of the image.
> -
>  @subsection qemu-img convert -n -o (since 4.2.0)
> 
>  All options specified in @option{-o} are image creation options, so
> @@ -383,3 +352,21 @@ trouble after a recent upgrade.
> 
>  The "autoload" parameter has been ignored since 2.12.0. All bitmaps
>  are automatically loaded from qcow2 images.
> +
> +@section Related binaries
> +
> +@subsection qemu-nbd --partition (removed in 5.0.0)
> +
> +The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
> +could only handle MBR partitions, and never correctly handled logical
> +partitions beyond partition 5.  Exporting a partition can still be
> +done by utilizing the @option{--image-opts} option with a raw blockdev
> +using the @code{offset} and @code{size} parameters layered on top of
> +any other existing blockdev. For example, if partition 1 is 100MiB
> +long starting at 1MiB, the old command:
> +
> +@code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
> +
> +can be rewritten as:
> +
> +@code{qemu-nbd -t --image-opts 
> driver=raw,offset=1M,size=100M,file.driver=qcow2,file.backing.driver=file,file.backing.filename=file.qcow2}

I know you just moved it from above, but isn’t this wrong?  Shouldn’t it
be s/backing/file/g?

Max

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