Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Tomasz Chmielewski]

Michael Jones wrote:

>> +#ifndef __ARMEB__
>> +#warning Little endian mode not supported
>> +#endif
> 
> Personally I'm less fussed about WAN / LE support. Anyone with any  
> sense will run ixp4xx boards doing such a specialised network  
> operation as BE. Also, NSLU2-Linux can't test this functionality with  
> our LE setup as we don't have this hardware on-board. You may just  
> want to declare a depends on ARMEB in Kconfig (with or without OR  
> (ARM || BROKEN) ) and have done with it - it's up to you.

Christian Hohnstaedt's work did support LE though.

Not all ixp4xx boards are by definition "doing such a specialised 
network operation".


Krzysztof, why is LE not supported?

Do you need access to ixp4xx that starts in LE mode?


-- 
Tomasz Chmielewski
http://wpkg.org

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Alexey Zaytsev]

On 5/8/07, Tomasz Chmielewski <mangoo@wpkg.org> wrote:
> Michael Jones wrote:
>
> >> +#ifndef __ARMEB__
> >> +#warning Little endian mode not supported
> >> +#endif
> >
> > Personally I'm less fussed about WAN / LE support. Anyone with any
> > sense will run ixp4xx boards doing such a specialised network
> > operation as BE. Also, NSLU2-Linux can't test this functionality with
> > our LE setup as we don't have this hardware on-board. You may just
> > want to declare a depends on ARMEB in Kconfig (with or without OR
> > (ARM || BROKEN) ) and have done with it - it's up to you.
>
> Christian Hohnstaedt's work did support LE though.
>
> Not all ixp4xx boards are by definition "doing such a specialised
> network operation".
>

I was always curious, why do people want to run ixp4xx in LE mode? What
are the benefits that overweight the obvious performance degradation?

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Michael-Luke Jones]

On 8 May 2007, at 09:48, Alexey Zaytsev wrote:

> I was always curious, why do people want to run ixp4xx in LE mode?  
> What
> are the benefits that overweight the obvious performance degradation?

Debian.
http://www.debian.org/ports/arm/

Michael-Luke

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Tomasz Chmielewski]

Alexey Zaytsev schrieb:
> On 5/8/07, Tomasz Chmielewski <mangoo@wpkg.org> wrote:
>> Michael Jones wrote:
>>
>> >> +#ifndef __ARMEB__
>> >> +#warning Little endian mode not supported
>> >> +#endif
>> >
>> > Personally I'm less fussed about WAN / LE support. Anyone with any
>> > sense will run ixp4xx boards doing such a specialised network
>> > operation as BE. Also, NSLU2-Linux can't test this functionality with
>> > our LE setup as we don't have this hardware on-board. You may just
>> > want to declare a depends on ARMEB in Kconfig (with or without OR
>> > (ARM || BROKEN) ) and have done with it - it's up to you.
>>
>> Christian Hohnstaedt's work did support LE though.
>>
>> Not all ixp4xx boards are by definition "doing such a specialised
>> network operation".
>>
> 
> I was always curious, why do people want to run ixp4xx in LE mode? What
> are the benefits that overweight the obvious performance degradation?

I guess the main reason, at least for me, is that there is only one 
distro that properly supports LE ARM: Debian.

It greatly simplifies management/administration of a higher number of 
devices, given the fact that Debian also supports other architectures 
(not just x86/64, sometimes PPC, like most distros do).


Not always network performance is to most important factor.


-- 
Tomasz Chmielewski
http://wpkg.org

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Gordon Farquharson]

On 5/8/07, Alexey Zaytsev <alexey.zaytsev@gmail.com> wrote:
> I was always curious, why do people want to run ixp4xx in LE mode? What
> are the benefits that overweight the obvious performance degradation?

Debian on the NSLU2 runs in LE, and it is pretty popular.

http://www.linuxdevices.com/news/NS3535328630.html

Gordon

-- 
Gordon Farquharson

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Krzysztof Halasa]

"Alexey Zaytsev" <alexey.zaytsev@gmail.com> writes:

> I was always curious, why do people want to run ixp4xx in LE mode? What
> are the benefits that overweight the obvious performance degradation?

Debian is indeed a valid reason.
I wonder if it would be much work to create BE Debian as well.
Simple automated process it seems, for most part at least.
-- 
Krzysztof Halasa

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Lennert Buytenhek]

On Tue, May 08, 2007 at 05:28:21PM +0200, Krzysztof Halasa wrote:

> > I was always curious, why do people want to run ixp4xx in LE mode? What
> > are the benefits that overweight the obvious performance degradation?
> 
> Debian is indeed a valid reason.
> I wonder if it would be much work to create BE Debian as well.

There _is_ an ARM BE version of Debian.

It's not an official port, but it's not maintained any worse than
the 'official' LE ARM Debian port is.

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Krzysztof Halasa]

Tomasz Chmielewski <mangoo@wpkg.org> writes:

> Krzysztof, why is LE not supported?

I'm not yet sure how to do it best.

The trivial way is really trivial, allocate a set of 1536-byte
buffers and make a swap+copy on RX and TX, but I want to
investigate the data-coherent approach first.

> Do you need access to ixp4xx that starts in LE mode?

No, I have a nice experimental machine so there is no problem
with that. I'd have to recompile my tools (GNU suite and rest
of the system) LE, but it's a simple thing, too.

I just want to have the functional drivers in the tree and
only then improve them. Doing all the work in a single step
is just impossible, the target moves way too fast (at least
for my limited time budget).
-- 
Krzysztof Halasa

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Krzysztof Halasa]

Lennert Buytenhek <buytenh@wantstofly.org> writes:

> There _is_ an ARM BE version of Debian.
>
> It's not an official port, but it's not maintained any worse than
> the 'official' LE ARM Debian port is.

Hmm... That changes a bit. Perhaps we should forget about
that LE thing then, and (at best) put that trivial workaround?
-- 
Krzysztof Halasa

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Tomasz Chmielewski]

Krzysztof Halasa schrieb:
> Lennert Buytenhek <buytenh@wantstofly.org> writes:
> 
>> There _is_ an ARM BE version of Debian.
>>
>> It's not an official port, but it's not maintained any worse than
>> the 'official' LE ARM Debian port is.
> 
> Hmm... That changes a bit. Perhaps we should forget about
> that LE thing then, and (at best) put that trivial workaround?

Does using ixp4xx on LE have any other drawbacks than inferior network 
performance?

And talking about network performance, what numbers are we talking about 
(LE vs BE; 30% performance hit on LE, more, or less)?


-- 
Tomasz Chmielewski
http://wpkg.org

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Krzysztof Halasa]

Tomasz Chmielewski <mangoo@wpkg.org> writes:

> Does using ixp4xx on LE have any other drawbacks than inferior network
> performance?

More memory is needed, something like max 600 KB for 2 Ethernet ports.

> And talking about network performance, what numbers are we talking
> about (LE vs BE; 30% performance hit on LE, more, or less)?

Haven't checked yet but I'd expect something like that.
-- 
Krzysztof Halasa

Why run ixp4xx LE? (Was: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS)

[Rod Whitby]

Michael-Luke Jones wrote:
> On 8 May 2007, at 09:48, Alexey Zaytsev wrote:
> 
>> I was always curious, why do people want to run ixp4xx in LE mode? What
>> are the benefits that overweight the obvious performance degradation?
> 
> Debian.
> http://www.debian.org/ports/arm/

And also out-of-kernel drivers for things like webcams, which have been
naively written for x86 little endian and have no concept of endian
neutrality.  In some cases it's just easier to run LE instead of
fighting with the driver code.

BTW, for the consumer-level IXP42x devices (like the NSLU2) the
performance difference is *completely* overwhelmed by slowness in the
rest of the system.

-- Rod

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Marcus Better]

Krzysztof Halasa wrote:
> Lennert Buytenhek <buytenh@wantstofly.org> writes:
>> There _is_ an ARM BE version of Debian.
>>
>> It's not an official port, but it's not maintained any worse than
>> the 'official' LE ARM Debian port is.

> Hmm... That changes a bit. Perhaps we should forget about
> that LE thing then, and (at best) put that trivial workaround?

Please keep in mind that users are unlikely to install an unofficial port
which lacks integration with the Debian infrastructure, security support
and other services. The arm architecture (LE) is currently the third most
popular in Debian, whereas I suspect (?) there are very few BE Debian
systems out there.

Marcus

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Koen Kooi]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Marcus Better schreef:
> Krzysztof Halasa wrote:
>> Lennert Buytenhek <buytenh@wantstofly.org> writes:
>>> There _is_ an ARM BE version of Debian.
>>>
>>> It's not an official port, but it's not maintained any worse than
>>> the 'official' LE ARM Debian port is.
> 
>> Hmm... That changes a bit. Perhaps we should forget about
>> that LE thing then, and (at best) put that trivial workaround?
> 
> Please keep in mind that users are unlikely to install an unofficial port
> which lacks integration with the Debian infrastructure, security support
> and other services.

Like the current debian EABI port?

regards,

Koen

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.5 (Darwin)

iD8DBQFGQZBsMkyGM64RGpERAj8HAJ4y0UAXGZBVTPd4VyJAi+/euaGS7gCgi+no
QRoEkQEToYgSp+vc8Gtwn2U=
=35DJ
-----END PGP SIGNATURE-----

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Lennert Buytenhek]

On Wed, May 09, 2007 at 10:58:06AM +0200, Marcus Better wrote:

> >> There _is_ an ARM BE version of Debian.
> >>
> >> It's not an official port, but it's not maintained any worse than
> >> the 'official' LE ARM Debian port is.
> 
> > Hmm... That changes a bit. Perhaps we should forget about
> > that LE thing then, and (at best) put that trivial workaround?
> 
> Please keep in mind that users are unlikely to install an unofficial port
> which lacks integration with the Debian infrastructure, security support
> and other services. The arm architecture (LE) is currently the third most
> popular in Debian, whereas I suspect (?) there are very few BE Debian
> systems out there.

Note that all of your arguments also apply to the experimental
EABI little-endian ARM port.

I.e.:
1. The EABI port is an unofficial port.
2. The EABI port is not integrated with the Debian infrastructure.
3. The EABI port lacks security support.

You could also argue that:
4. "There is no reason to use EABI -- old-ABI works just as well."
5. "The perceived floating point speedups that EABI gives are
   completely drowned out by the slowness of the rest of the system."
6. "A lot of programs assume old-ABI behavior, it is too much work
   to patch them all."

Does that mean that the Debian ARM people have their heads so far
up their collective asses that they think that every form of change
is bad and are unable to accept that some forms of change might be
for the better?

I think you've just summarised why I don't like working on Debian.

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Marcus Better]

[-- Attachment #1: Type: text/plain, Size: 526 bytes --]

Lennert Buytenhek wrote:
> Does that mean that the Debian ARM people have their heads so far
> up their collective asses that they think that every form of change
> is bad and are unable to accept that some forms of change might be
> for the better?

Well, I am not one of the Debian ARM people, just a user... and I do hope the 
EABI port becomes supported in the future! But in the meatime there is a 
crowd of users running Debian on consumer devices like the NSLU2, and they 
need a LE network driver.

Marcus

[-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --]

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Lennert Buytenhek]

On Wed, May 09, 2007 at 11:35:03AM +0200, Marcus Better wrote:

> > Does that mean that the Debian ARM people have their heads so far
> > up their collective asses that they think that every form of change
> > is bad and are unable to accept that some forms of change might be
> > for the better?
> 
> Well, I am not one of the Debian ARM people, just a user... and I
> do hope the EABI port becomes supported in the future! But in the
> meatime there is a crowd of users running Debian on consumer devices
> like the NSLU2, and they need a LE network driver.

"There's a crowd of users running Linux on TCP offload capable
cards, and they need TCP offload support in Linux."

The people who need a LE network driver can use Christian's driver,
as Christian's driver works in LE just fine.  The people who care
about LE support can add LE support to the driver that Krzysztof wrote.

I don't think that not supporting LE is a reason not to merge
Krzysztof's driver.  Don't make supporting LE systems Krzysztof's
problem.

Krzysztof has written an excellent driver, and while it would be 100%
Debian style to reject his driver just because it doesn't support LE[*],
thankfully, Linux is not Debian.  Please don't turn Linux into Debian.


[*] And if he were to complain about this, he would get slapped with
    the standard "Our priorities are our users and free software"
    Debian Social Contract rhetoric -- thank $DEITY we don't have a
    Linux Kernel Social Contract with the same bullshit in it.

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[David Acker]

Lennert Buytenhek wrote:
> The people who need a LE network driver can use Christian's driver,
> as Christian's driver works in LE just fine.  The people who care
> about LE support can add LE support to the driver that Krzysztof wrote.
> 
> I don't think that not supporting LE is a reason not to merge
> Krzysztof's driver.  Don't make supporting LE systems Krzysztof's
> problem.
> 
> Krzysztof has written an excellent driver, and while it would be 100%
> Debian style to reject his driver just because it doesn't support LE[*],
> thankfully, Linux is not Debian.  Please don't turn Linux into Debian.

I am using the ixp425 on the avila from gateworks.  It only has 16 MB of 
  flash built in.  We needed to squeeze a production and a failsafe 
linux inside that so debian was not an option.  I found intel's original 
drivers horrible to read, maintain, and use.  We are using Cristian's 
driver (rev 0.2.1) and are preparing to go to his latest for the crypto 
support.  I only had one bug in 0.2.1, which is fixed in later versions. 
  I would love to see mail line support for this device, including the 
ethernet ports and the crypto capabilities.

We run in big endian despite the extra difficulty in toolset setup and 
finding lots of brain0-damaged-designed-for-x86 code.  We already can 
use up the CPU when we have the mini-pci slots populated with 802.11g 
radios and the ethernet port in use.  Swapping packets would kill us. 
Never mind if we do any kind of software based crypto!  For those of us 
in the embedded space, performance matters.

Big endian is the natural setup for the NPEs on this hardware according 
to the intel documentation.  Please don't stop this driver from moving 
forward so that a few folks can run their hardware in slow mode.

-Ack

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Michael-Luke Jones]

On 9 May 2007, at 15:22, David Acker wrote:
> Big endian is the natural setup for the NPEs on this hardware  
> according to the intel documentation.  Please don't stop this  
> driver from moving forward so that a few folks can run their  
> hardware in slow mode.

No-one is saying that this driver should not be mainlined before it  
has LE support. All that I said was:

> Personally I'd like LE ethernet tested and working before we push.

The alternative would be to explicitly state in Kconfig that LE arm  
is broken with this driver, so that this could be fixed later.

Please can we not blow this out of proportion, it really isn't that  
big a deal. The irony is that fixing Krzysztof's driver to work on LE  
will probably be quite easy, given that we already have a working LE  
driver from Christian.

Michael-Luke

PS: It really isn't just 'a few folks' - at NSLU2-Linux we have 5000  
people who have downloaded Debian/LE for NSLU2 and are currently  
using Christian's driver with great success. We would just like to  
replicate that support with this new driver.

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Christoph Hellwig]

On Tue, May 08, 2007 at 10:29:03AM +0200, Tomasz Chmielewski wrote:
> Michael Jones wrote:
> 
> >>+#ifndef __ARMEB__
> >>+#warning Little endian mode not supported
> >>+#endif
> >
> >Personally I'm less fussed about WAN / LE support. Anyone with any  
> >sense will run ixp4xx boards doing such a specialised network  
> >operation as BE. Also, NSLU2-Linux can't test this functionality with  
> >our LE setup as we don't have this hardware on-board. You may just  
> >want to declare a depends on ARMEB in Kconfig (with or without OR  
> >(ARM || BROKEN) ) and have done with it - it's up to you.
> 
> Christian Hohnstaedt's work did support LE though.
> 
> Not all ixp4xx boards are by definition "doing such a specialised 
> network operation".
> 
> 
> Krzysztof, why is LE not supported?
> 
> Do you need access to ixp4xx that starts in LE mode?

Not even trying to support LE is a clear merge blocker.  Maybe Krzysztof
can't actually test it himself, which is fine - but not even pretending
to be endian clean is not what proper Linux drivers do.

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Michael-Luke Jones]

On 16 May 2007, at 08:13, Christoph Hellwig wrote:

> Not even trying to support LE is a clear merge blocker.  Maybe  
> Krzysztof
> can't actually test it himself, which is fine - but not even  
> pretending
> to be endian clean is not what proper Linux drivers do.

w.r.t this comment, a working implementation LE implementation can be  
viewed here:

http://www.hohnstaedt.de/ixp_npe/0.3.1/ixp4xx_npe_driver-0.3.1.diff

Search in this file for "swap the payload of the SKB" (it's in  
mac_driver.c)

Michael-Luke Jones

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Lennert Buytenhek]

On Wed, May 16, 2007 at 08:13:01AM +0100, Christoph Hellwig wrote:

> > >>+#ifndef __ARMEB__
> > >>+#warning Little endian mode not supported
> > >>+#endif
> > >
> > >Personally I'm less fussed about WAN / LE support. Anyone with any  
> > >sense will run ixp4xx boards doing such a specialised network  
> > >operation as BE. Also, NSLU2-Linux can't test this functionality with  
> > >our LE setup as we don't have this hardware on-board. You may just  
> > >want to declare a depends on ARMEB in Kconfig (with or without OR  
> > >(ARM || BROKEN) ) and have done with it - it's up to you.
> > 
> > Christian Hohnstaedt's work did support LE though.
> > 
> > Not all ixp4xx boards are by definition "doing such a specialised 
> > network operation".
> > 
> > Krzysztof, why is LE not supported?
> > 
> > Do you need access to ixp4xx that starts in LE mode?
> 
> Not even trying to support LE is a clear merge blocker.  Maybe
> Krzysztof can't actually test it himself, which is fine - but
> not even pretending to be endian clean is not what proper Linux
> drivers do.

The issue is not that the driver is not 'endian clean'.

This is a driver for an on-chip ethernet MAC on an ARM CPU.  I.e. the
ethernet MAC is on the CPU itself, it's not some kind of PCI device or
something like that.  The ARM CPU in question can be run in either
little endian or big endian mode.  Making a driver work in both modes
of operation is generally not just an issue of adding a couple of
be32_to_cpu()s in the right places.

For example, intel IXP2000 and IXP23xx CPU support in arch/arm only
supports big-endian mode of operation, and none of the associated
drivers support little-endian mode.

Most of the other CPU support in arch/arm only supports
little-endian mode, and none of the associated drivers support
big-endian mode.  According to your criterion, that would mean that
most of the ARM drivers (alsa, usb, framebuffer, networking, etc.)
should never have been accepted in the kernel tree in the first place.

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Michael-Luke Jones]

On 16 May 2007, at 10:41, Lennert Buytenhek wrote:
> Making a driver work in both modes
> of operation is generally not just an issue of adding a couple of
> be32_to_cpu()s in the right places.

While this comment is technically correct, Christian's driver  
achieves endian agnostic operation with only 10 additional lines of  
code [1].

Thus, there is no reason to assume that gaining LE support will be a  
major issue.

Michael-Luke

[1] http://www.hohnstaedt.de/ixp_npe/0.3.1/ixp4xx_npe_driver-0.3.1.diff
Search in this file for "swap the payload of the SKB" (it's in  
mac_driver.c)

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Rod Whitby]

Lots of people wrote:
> Lots of huffing and puffing about endian support by this driver ...

For what it's worth, the NSLU2-Linux project (which has over 10,000
known users of our custom ixp4xx firmware, most of which will eventually
be users of this new driver) is *endian-neutral*.

We support both big-endian and little-endian usage of the ixp4xx in a
number of consumer devices like the NSLU2, NAS100d, DSMG600, and FSG3.

We are very interested in getting this driver into mainline in the most
expedient and correct fashion acceptable to the relevant mainline
maintainers.  We have also discussed this situation with the author of
the previous set of ixp4xx open-source ethernet driver patches, and he
also recommends that we put our support behind this new set of patches.

So, if the author of these patches wishes to concentrate on big-endian
support first, then we will not say (and have not said) anything which
will block inclusion of a big-endian only version of this driver.

In parallel to this initial upstream push, we will be working with the
author to make sure that this driver supports little-endian devices as
well (as we are endian-neutral in our project's support of consumer
devices based on the ixp4xx).  If we get this done before upstream
acceptance of the big-endian version, that will be great.  If we don't,
then we'll work to hit the next merge window.  We will create a
functionally correct little-endian version first (the simple
byte-swapping implementation) and will work on a performance-enhanced
version later (if that is even possible without prohibitive massive
upstream changes).

There simply is no reason for everyone to be arguing about this.

Remember that what we are seeing here is an open-source replacement for
a long-time proprietary driver.  We should all rejoice in that, support
the author of these patches, and not fight amongst ourselves.

-- Rod Whitby
-- NSLU2-Linux Project Lead

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Lennert Buytenhek]

On Wed, May 16, 2007 at 08:16:38PM +0930, Rod Whitby wrote:

> So, if the author of these patches wishes to concentrate on big-endian
> support first, then we will not say (and have not said) anything which
> will block inclusion of a big-endian only version of this driver.

The NSLU2 people are the ones here that are saying that the driver
should really support LE (because that is what they happen to be
using, the rest of the world runs the ixp4xx in BE), and they keep
saying that it would be so easy to make a patch to add LE support,
but so far they haven't produced such a patch.

Please just write the patch and let's get this over with.

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Rod Whitby]

Lennert Buytenhek wrote:
> On Wed, May 16, 2007 at 08:16:38PM +0930, Rod Whitby wrote:
>> So, if the author of these patches wishes to concentrate on big-endian
>> support first, then we will not say (and have not said) anything which
>> will block inclusion of a big-endian only version of this driver.
> 
> The NSLU2 people are the ones here that are saying that the driver
> should really support LE (because that is what they happen to be
> using, the rest of the world runs the ixp4xx in BE)

I'll repeat again.  NSLU2-Linux supports both BE and LE.  We have about
5,000 users running BE and about 5,000 users running LE.  Perhaps you're
confusing the NSLU2-Linux project (which official supports both endians
equally) with the Debian project (which official supports only LE, and
has an unofficial BE port).

One NSLU2-Linux person said they would prefer the driver to support LE,
but would be happy for it to be marked BE only in the Kconfig as an
alternative.  That is consistent with what I wrote in my message.

> Please just write the patch and let's get this over with.

Please let's just stop arguing about it.  If a patch appears before it
gets merged, then great.  If it doesn't then it will appear at a later date.

-- Rod

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Lennert Buytenhek]

On Wed, May 16, 2007 at 09:05:18PM +0930, Rod Whitby wrote:

> >> So, if the author of these patches wishes to concentrate on big-endian
> >> support first, then we will not say (and have not said) anything which
> >> will block inclusion of a big-endian only version of this driver.
> > 
> > The NSLU2 people are the ones here that are saying that the driver
> > should really support LE (because that is what they happen to be
> > using, the rest of the world runs the ixp4xx in BE)
> 
> I'll repeat again.  NSLU2-Linux supports both BE and LE.  We have
> about 5,000 users running BE and about 5,000 users running LE.

Perhaps, but somehow I don't think that we'd have seen any reaction
if the submitted driver had only supported LE and not BE.


> > Please just write the patch and let's get this over with.
> 
> Please let's just stop arguing about it.  If a patch appears before
> it gets merged, then great.  If it doesn't then it will appear at a
> later date.

Great.  I agree.

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Krzysztof Halasa]

Christoph Hellwig <hch@infradead.org> writes:

> Not even trying to support LE is a clear merge blocker.  Maybe Krzysztof
> can't actually test it himself, which is fine - but not even pretending
> to be endian clean is not what proper Linux drivers do.

The drivers can only work with IXP4xx CPU and that's not the typical
endianess problem cross-platform drivers sometimes have.

There is different functionality required with LE mode, unless some
other arch changes are implemented (which I'm now researching, if
I have some time of course).
-- 
Krzysztof Halasa

Re: [PATCH] Intel IXP4xx network drivers v.2 - Ethernet and HSS

[Krzysztof Halasa]

Rod Whitby <rod@whitby.id.au> writes:

> Please let's just stop arguing about it.  If a patch appears before it
> gets merged, then great.  If it doesn't then it will appear at a later date.

Sure. The "swapping" patch is trivial and I can add it if needed
at some point but I hope we can do that "data coherency mode" right.

Personally I'd be pleased if I could run the board LE instead
of BE, with no performance penalty.
-- 
Krzysztof Halasa