[Ksummit-2008-discuss] A suggestion for Linux 3.0

[Mauro Carvalho Chehab]

On Sat, 30 Aug 2008 18:31:44 +0200
Jean Delvare <khali at linux-fr.org> wrote:

> Hi Alan,
> 
> On Sat, 30 Aug 2008 15:55:31 +0100, Alan Cox wrote:
> > Having spent ages wading through old broken ISA drivers some of which
> > clearly have no users as they've not worked for years I want throw in
> > another proposal for the kernel summit
> > 
> > At some point soon we add all the old legacy ISA drivers (barring the odd
> > ones that turn up in embedded chipsets on LPC bus) into the
> > feature-removal list and declare an 'ISA death' flag day which we brand
> > 2.8 or 3.0 or something so everyone knows that we are having a single
> > clean 'throw out' of old junk.
> 
> I don't get the idea. If some drivers are old and unused and we want to
> delete them, let's just delete them. No need to wait for 2.8. But I
> fail to see why we should remove all ISA drivers because some ISA
> drivers are broken. I still use at least one ISA driver (3c509). Do not
> forget that one strength of Linux is that it runs fine on old hardware.
> I would certainly like it to stay that way.

I agree with Alan's proposal.

Kernel still runs on old hardware, but this doesn't mean that you'll be able to
actually run any current distro on it. I used to have one of the latest desktop
from ISA days (1998? hmm.. maybe older) with a hybrid ISA/PCI bus, a pentium
pro and 80M SRAM (originally, I bought it with 16M) and 1.2 Gb hard drive. 

The the last time I tried to use that machine (a few years ago), I couldn't find
any distro with a newer kernel 2.6 that performed fine (and capable on
installing on its disk), even with a light X11 running on it. For it to work
with some performance, I needed to use a 2.4 based distro (those distros
"ready" for 2.6, launched during late 2.5 kernels). That distro were able to
install on my disk, and allowed me to have a 2.6 kernel on it. It took an entire
night to compile). After the job, I was almost without free space.

So, except for us to be proud of that, I can't see any practical sense on
keeping support for hardware with 10+ years old.

So, I really can't see much sense on keep supporting ISA (I would also add MCA)
bus. IMO, we should put a date for its removal from kernel. If some user still
needs to use it, it may still run with an older kernel.

> > It would also be a chance to throw out a whole pile of other "legacy"
> > things like ipt_tos, bzImage symlinks, ancient SCTP options, ancient
> > lmsensor support, V4L1 only driver stuff etc.

In the case of V4L1, I don't think it would be a good idea just to remove all
V4L1 only drivers. Legacy V4L stuff may be broken into a few categories:

	- Legacy ISA radio - all of them are currently using V4L2 API. We may
remove it together with ISA removal. Otherwise, I don't see any practical
reason for their removal, since they just works;

	- V4L1 only Zoran driver - AFAIK, there are not-so-old PCI boards with
those chips. It seems valuable to make they work with V4L2. There's one developer
working on it, but I don't think this is his top development priority;

	- a few V4L1 webcam drivers. We need to check case by case. There are
still some cameras that may be valuable to migrate its support to another
driver, like gspca. One developer is interested on doing this job;

	- legacy PCI ID's on drivers that are still used by newer hardware.
Bttv is the life example of such hardware: still today companies are selling
bttv devices. The driver has about 10 years old (I still have an ISA bttv board
somewhere). I don't see any practical reason for removing support for those devices.

Cheers,
Mauro