undefined | Better HN

0 pointsAnthonyMouse9y ago0 comments

> My naive assumption is that code reuse across platforms is a good thing, I'd love to understand why this isn't the case here or what the concrete arguments are against it.

A driver is inherently platform-specific. It's glue that ties the hardware to the operating system. The only "correct" way to have one driver work on multiple operating systems is for the operating systems to all use the same driver model.

The ugly way is to create your own hardware abstraction layer and then write a translation layer between that and each operating system, because that's complicated and hideous.

But it's especially silly because Linux accepts suitable contributed code, so you could instead use the native Linux model as your "intermediary layer" and fix Linux if it isn't suitable in some way. And then translate that to what the closed operating system you can't modify uses.

The result is that the Linux people are happier and you have one less translation layer to maintain.

0 comments

comex9y ago

That might run into license issues. If you want to avoid licensing the other versions of your driver under GPLv2, you'd have to carefully avoid copying any code from the main kernel into your translation layer (rewriting any helper functions you end up using), and even then there's the idea of API copyright to contend with.

One might ask whether it is desirable to avoid the GPL, and there are a lot of arguments on both sides there, but it's certainly easy to run into issues when you have a GPL licensed module designed to be linked into a proprietary program (kernel).

AnthonyMouseOP9y ago

> If you want to avoid licensing the other versions of your driver under GPLv2, you'd have to carefully avoid copying any code from the main kernel into your translation layer (rewriting any helper functions you end up using), and even then there's the idea of API copyright to contend with.

Isn't the point supposed to be to not have other versions of your driver, so you can use the same one on every platform?

comex9y ago

By "other versions" I mean the codebase used for a given non-Linux platform, which would (hypothetically) include most of the Linux driver's code plus a translation layer from Linux APIs to that platform's.

AnthonyMouseOP9y ago

The translation layer isn't where the interesting bits are. The parts hardware companies want to keep secret are the hardware-specific parts, not the OS-specific parts. It might even help them to open source the translation layers because then others could potentially use them and shoulder some of the maintenance cost.

I can't speak to the legal status of GPL drivers for Windows, but several seem to exist already (e.g. Windows ext4 driver), and if they were actually worried about it they could always get explicit permission from the copyright holders of the relevant code. Either they say yes and you're fine or they say no you know what pieces of code to replace.

EpicEng9y ago

>But it's especially silly because Linux accepts suitable contributed code, so you could instead use the native Linux model as your "intermediary layer" and fix Linux if it isn't suitable in some way. And then translate that to what the closed operating system you can't modify uses.

But Linux repesents a tiny portion of the gaming community, so that approach would make no sense at all for a GPU vendor. C'mon.

aseipp9y ago

Then they aren't going to get their driver upstream. End of story. Kernel developers have already done this once (Dave hinted at Exynos drivers in the past in his other posts) and it was a large amount of work to un-screw the pooch once all this crap came along.

I know that Linux people really really just want the kernel to take one for the team so they can have GPUs because that's just the goal, and clearly the goal is good and the means don't matter at all and everything else is irrelevant. 100,000 lines of crap code, 200k? 500k? Who cares, it's all in the name of GPUs clearly. It's obviously worth it no matter what.

But the kernel developers do not see it that way, and for good reason -- because once it's in tree, they are all on the hook for it and they all have to deal with the swamp, the added complexity, the maintenance, the un-fucking of this entire HAL, etc etc.

Having worked on a large open source project, I can assure you, it sucks when you have to say "This isn't acceptable and we aren't merging it", even when it's a feature the users want, and one someone worked on for a long time. It is also, almost always, the right thing to do in the long run (and several of those features did come back, in acceptable ways, in our case).

AnthonyMouseOP9y ago

> But Linux repesents a tiny portion of the gaming community, so that approach would make no sense at all for a GPU vendor. C'mon.

The growth market for GPUs is GPGPU and servers. And Linux represents a large portion of the programming and server communities.

More to the point, as soon as you support Linux at all then it doesn't matter who has more share, it's still less work to do the above than have to maintain another translation layer.

2 more replies

nindalf9y ago

I agree with you almost entirely, except the part about fixing Linux. If the abstraction that Linux provides isn't suitable for some reason, it probably isn't straightforward to change it because of compatibility with existing code.

caf9y ago

That's not so much a concern within the kernel boundary, which is the case that applies here. If you have a compelling reason to redesign an internal API, you "just" have to fix up all the code across the tree that consumes it. Changes are regularly made to the internal VFS interfaces, for example.

wtallis9y ago

It's also often the case that kernel-driver interfaces are extended without breaking compatibility. In those cases, you want to ensure that the extensions are suitable for more than one driver to consume.

posterboy9y ago

Or future changes in the linux target need to be translated to all other target wrappers.

j / k navigate · click thread line to collapse

0 comments

comex9y ago

AnthonyMouseOP9y ago

Isn't the point supposed to be to not have other versions of your driver, so you can use the same one on every platform?

comex9y ago

AnthonyMouseOP9y ago

EpicEng9y ago

But Linux repesents a tiny portion of the gaming community, so that approach would make no sense at all for a GPU vendor. C'mon.

aseipp9y ago

AnthonyMouseOP9y ago

> But Linux repesents a tiny portion of the gaming community, so that approach would make no sense at all for a GPU vendor. C'mon.

The growth market for GPUs is GPGPU and servers. And Linux represents a large portion of the programming and server communities.

More to the point, as soon as you support Linux at all then it doesn't matter who has more share, it's still less work to do the above than have to maintain another translation layer.

2 more replies

nindalf9y ago

caf9y ago

wtallis9y ago

posterboy9y ago

Or future changes in the linux target need to be translated to all other target wrappers.

j / k navigate · click thread line to collapse