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From: Lawrence Stewart <lstewart@freebsd.org>
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To: John Baldwin <jhb@freebsd.org>
Subject: Re: [PATCH] Don't imply TCP and UDP socket options are bitmasks
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On 01/16/13 06:16, John Baldwin wrote:
> On Tuesday, January 15, 2013 3:49:33 am Lawrence Stewart wrote:
>> On 01/15/13 07:50, John Baldwin wrote:
>>> The constants used for TCP and UDP socket options (TCP_NODELAY, etc.) are 
>>> currently defined as hex values that are individual bits.  However, socket 
>>> options are never masked together, they are used as a simple enumeration of 
>>> discrete values.  Using a bitmask forces us to run out of bits and makes it 
>>> harder for vendors to try to use a high range of values for local custom 
>>> options (hoping that they never conflict with a new option value added in 
>>> stock FreeBSD).
>>
>> Yup. Should we be explicitly #defining the boundary between "bits
>> reserved for FreeBSD" and "bits for private vendor use"?
> 
> Oh, we could if you wanted.  I'm using 0x1000 locally for both TCP and UDP,
> but those are completely arbitrary values.  Saner ones might be 0x8000000 if
> we want to do that explicitly.  We could perhaps just say that is true for all
> socket option levels (that is, just define one SO_VENDOR constant or some such
> but say it applies to all levels)?

A single SO_VENDOR applied to all levels sounds good to me.

Cheers,
Lawrence