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Re: [Qemu-devel] [PATCH v2] nbd: Flip qemu-nbd to prefer newstyle; add -
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v2] nbd: Flip qemu-nbd to prefer newstyle; add -O for old behavior |
Date: |
Wed, 3 Oct 2018 15:43:37 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 |
On 10/3/18 12:55 PM, Eric Blake wrote:
Oldstyle NBD negotiation cannot perform any of the extensions that
we have recently been relying on. While you can always pass -x ""
to get newstyle negotiation, these days, it is better to just default
to newstyle (with an empty export name) and fall back to oldstyle
only on an explicit request.
qemu as client can manage either style since 2.6.0, commit 69b49502d8
For comparison:
nbdkit 1.3 switched its default to newstyle (Jan 2018):
https://github.com/libguestfs/nbdkit/commit/b2a8aecc
https://github.com/libguestfs/nbdkit/commit/8158e773
nbd 3.10 dropped oldstyle long ago (Mar 2015):
https://github.com/NetworkBlockDevice/nbd/commit/36940193
Signed-off-by: Eric Blake <address@hidden>
---
v2: improve 'qemu-nbd --help', drop redundant variable 'newproto'
---
qemu-nbd.c | 37 +++++++++++++++++++++++--------------
1 file changed, 23 insertions(+), 14 deletions(-)
But I still forgot to document it in qemu-nbd.texi.
I'm dropping this patch in favor of Vladimir's stronger series, now that
Rich has agreed with my observation that nbdkit can bridge the needs of
any non-qemu client that still only talks oldstyle.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org