Re: [Qemu-block] [PATCH 0/2] nbd server: drop old-style negotiation

[Vladimir Sementsov-Ogievskiy]

03.10.2018 21:08, Eric Blake wrote:
> On 10/3/18 12:59 PM, Vladimir Sementsov-Ogievskiy wrote:
>> 03.10.2018 20:32, Eric Blake wrote:
>> On 10/3/18 12:02 PM, Vladimir Sementsov-Ogievskiy wrote:
>> It's unexpected behavior that without -x option qemu-nbd do old-style
>> negotiation. Let's use "" as a default name instead (as it is already
>> done if tls is used) and therefore, drop old-style negotiation from
>> Qemu NBD server.
>
> Hmm, your email quoting style changed from prior emails that used to 
> prepend '>' when quoting, making it harder to tell where the text you 
> are quoting ends,...

I didn't change anything...

>
>>
>> Oddly enough, I wrote a similar patch in parallel, and am only now 
>> just seeing your mail. Yours is a bit stronger than mine (I added 
>> 'qemu-nbd -O' to allow explicit fallback to oldstyle, while you 
>> ripped it out altogether).  The client can negotiate either style, so 
>> we don't need an option on the client side; rather, this is all about 
>> what the server should do by default.
>>
>> https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg00568.html
>>
>> Does anyone have a preference between the two? Here's the last time 
>> it was discussed:
>>
>> https://lists.gnu.org/archive/html/qemu-devel/2018-08/msg03252.html
>>
>
> and your reply begins.
>
>> Hm, I think everyone who like new-style should answer that he don't 
>> care (except stricter way is a bit better: don't have options and 
>> code which we don't need).
>> But if there is someone who has client which support only old-style 
>> negotiation his unhappiness (in case of strict way) will outweigh all 
>> our "bits":)
>>
>> I'm from the first group). But let's chose your patch
>
> My argument in favor of your patch over mine: nbdkit is a GREAT 
> testbed for forcing all sorts of integration testing scenarios, 
> including oldstyle servers.  Also, it includes a plugin for 
> translating between new and oldstyle at will.  That is, if we ever 
> legitimately encounter a client that can only talk oldstyle, but qemu 
> only talks newstyle, we just tell the user to connect:
>
> old client => nbdkit -o nbd => newstyle qemu
>
> and then qemu doesn't have to worry about oldstyle because nbdkit does 
> instead.
>

this is a bit more difficult and more overhead than option in Qemu.. But 
I don't sure we should care about

-- 
Best regards,
Vladimir