[PATCH] Add -iglx & +iglx to Xserver.man

[Alan Coopersmith]

On 11/25/14 10:36 PM, Robert Morell wrote:
> On Tue, Nov 25, 2014 at 07:26:14PM -0800, Alan Coopersmith wrote:
>> Covers the current state after commits 99f0365b1fbdfd9238b9f,
>> d0da0e9c3bb8fe0cd4879, & e3aa13b8d63ea2fba6eb4 were all applied.
>>
>> Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
>> ---
>>   man/Xserver.man |   10 ++++++++++
>>   1 file changed, 10 insertions(+)
>>
>> diff --git a/man/Xserver.man b/man/Xserver.man
>> index c03830c..69ff626 100644
>> --- a/man/Xserver.man
>> +++ b/man/Xserver.man
>> @@ -181,6 +181,16 @@ prints a usage message.
>>   .B \-I
>>   causes all remaining command line arguments to be ignored.
>>   .TP 8
>> +.B \-iglx
>> +Prohibit creating indirect GLX contexts.  Indirect GLX is of limited use,
>> +since it only supports up to OpenGL 1.4; it's slower than direct contexts;
>
> Technically, there exists protocol for much if not all of OpenGL 2.1,
> and some extensions beyond that.  But not all server and client
> implementations support it...

Sorry, I copied that from the comments in the commit that actually created the
options, and took Eric's word for it:

http://cgit.freedesktop.org/xorg/xserver/commit/?id=99f0365b1fbdfd9238b9f5cc28491e4e6c7324f1

Would "only fully supports up to OpenGL 1.4, with partial support for
OpenGL 2.1 and some later extensions" be more accurate?  Or is there
a better wording someone can think of?

>> +and it opens a large attack surface for protocol parsing errors.
>> +This is the default unless +iglx is specified, though it may not be honored
>> +by GLX implementations other than the one provided with the X server.
>
> For what it's worth, in case anyone finds this thread in the archives,
> I'll point out that NVIDIA's implementation does honor this option in
> newer drivers, which contain the following entry in the changelog:
>
>      * Implemented support for disabling indirect GLX context creation using
>        the -iglx option available on X.Org server release 1.16 and newer.  Note
>        that future X.Org server releases may make the -iglx option the default.
>        To re-enable support for indirect GLX on such servers, use the +iglx
>        option.

That's good - perhaps we can drop that qualification if both NVIDIA & AMD
will be supporting the check in their Xorg 1.17 ABI compatible versions.

I was thinking of older driver versions when I'd written it, but obviously,
due to ABI changes, there shouldn't be many (any?) GLX implementations that
can both be loaded by Xorg 1.17 and do not support this flag, so I don't
know why I was thinking of that.

>
> But your text above is still accurate, so other than perhaps softening
> the OpenGL 1.4 limitation,
>
> Reviewed-by: Robert Morell <rmorell at nvidia.com>
>
>> +.TP 8
>> +.B +iglx
>> +Allow creating indirect GLX contexts.
>> +.TP 8
>>   .B \-maxbigreqsize \fIsize\fP
>>   sets the maximum big request to
>>   .I size
>> --
>> 1.7.9.2


-- 
	-Alan Coopersmith-              alan.coopersmith at oracle.com
	 Oracle Solaris Engineering - http://blogs.oracle.com/alanc