EXPORT_SYMBOL_GPL for __symbol_get replacing EXPORT_SYMBOL for deprecated inter_module_get

Yuri Vilmanis
2005-04-13T09:25:57Z

I believe that, in general, new functions which replace deprecated functions
which were exported as EXPORT_SYMBOL, should also be exported as
EXPORT_SYMBOL, not as EXPORT_SYMBOL_GPL. The reason I say this is because
deprecation of old functions breaks old modules and drivers that use them,
and changing the level of GPL strictness of the function prevents these old
modules being updated and used with newer kernels.

The case in point for me is ATI's binary openGL accelerated drivers (fglrx) -
these used inter_module_get() to communicate with the agp gart module, for
obvious reasons - this AGP communication is essential to the functionality of
the driver. No, I don't like ATI only having closed-source drivers any more
than you, but given the extremely competetive nature of high end video card
sales, I can see why they want to do it this way. The point is that now, as
of 2.6.11-? or 2.6.12-? (not sure of the exact revision), the
inter_module_get() functions has been removed, and the functionality can only
be got (as far as I can tell) through use of the symbol_get() function.

Am I take it to mean that no closed-source / binary-only driver may use AGP
acceleration in the future, including ones that have in the past? Or if an
alternate method of AGP accelerated access exists (I dont know the kernel
well enough to know for sure), does this mean companies which have at least
been respectful enough to have provided linux drivers must now rewrite them
to use an entirely different methodology in their drivers, write entirely new
agp drivers which will then probably also be closed-source, and are likely to
cause further problems down the line, or GPL drivers which contain code
important to the competetiveness of the company? I think this is not a good
situation for linux users or hardware manufacturers, and indeed shows Linux
itself in a bad light.

I respect and agree with the use of EXPORT_SYMBOL_GPL to maintain new
*software* functionality added by kernel developers, but when this prevents
propriatary drivers from using advanced *hardware* features of common
hardware connectivity devices like an AGP port, its silliness, plain and
simple (I think this applies equally to other devices which are required for
the connection of the device for which the propriatary driver was created,
such as USB, PCI, serial, AGP, PCIExpress, firewire, IDA/SATA etcetc where
DMA, ATA, fast serial (as provided by some Maxim chips with accelarated
slew-rate) or other advanced advanced transfer modes are provided and enabled
by the *harware*).

Also, deprecating non-GPL-strict functionality and replacing it with
GPL-strict funtionality is just as bad, in my view, as going through the
kernel and randomly changing instance of EXPORT_SYMBOL to EXPORT_SYMBOL_GPL -
it has the same effect, of breaking established propriatary drivers, and
forcing companies which do not feel that they can GPL the source and maintain
their competetive advantage, to rewrite their drivers to use alternate
methods (which they therefore have no certainty will be available in the
future either), or dropping support altogether (which I'm sure nobody really
wants). If Linux had a near-monopoly market share, it might be possible to
get away with such strong-arm tactics in the interest of spreading the FSF
distribution philosophy - but then again, look what similar tactics did to
public opinion of the distribution philosophy of a certain Redmond company
which did have near-monopoly market share.... I shudder at the thought of the
point being applicable to Linux, but I think it must be made in order to
prevent it becoming creepingly (and creepily) more valid in the future.

The case of inter_module_get deprecation and replacement with symbol_get
embodies both sides: it makes a non-GPL export into a GPL export (yes, its
now called by a different name, and the backend has changed, but the first
change is cosmetic and the second change is internal), and it also prevents
closed-source drivers from using functionality of a device that they have no
choice but to connect through, and require for competetive performance.

To sum up:
1) Please make symbol_get a non-GPL export, so that those of us with hardware
that needs it can continue to use it (eg anyone with an ATI video card that
wants to use the shaders and extensions that are the point in favour over
NVidia offerings)
2) I think the use of GPL symbol exports should be more carefully monitored
where it affects existing closed-source drivers and designed-in hardware
functionality like AGP, to avoid alienating companies which have been polite
enough to come half way and supported their hardware under this great OS.

After all, I think we all want Linux to win by being the best - not by going
around shouting "Thou shalt use the GPL, it ownz your propriatary
distribution model and if you dont use it youre a moron and we wont let you
use Linux" at passing strangers (not that this is likely to work anyway).

-Yuri

PS - This was not meant to be a rant, start a flamewar or even tread on
anyones toes, really.... I'm just a bit annoyed that I can't do my shader
development while running a nice bleeding-edge kernel, and apprehensive of
not being able to do my shader development in a few months/years when this
kernel is officially OldHat (TM, Inc, or whatever)