[parisc-linux] Re: Fw: Another problem with making things static

[parisc-linux] Re: Fw: Another problem with making things static

[James Bottomley]

On Sat, 2007-02-10 at 22:43 +0100, Adrian Bunk wrote:
> First of all thanks to Andrew for forwarding this email to me - it's 
> otherwise a bit hard to defend against an email that doesn't reach me.

I think if you read the email you'll find it didn't actually attack you
at all ... I was careful only to ask for a change of policy before
accepting a patch that does nothing but make a function static.

> >...
> > 
> > We're going to need this one reverting for parisc.  If you remember
> > we've been trying to push a compat_sys_rt_sigqueueinfo but Andi keeps
> > objecting, so it's remained local to our tree (an hence so has the
> > symbol usage).
> > 
> > However, can we *please* stop this indiscriminate rampage through all
> > the sybsystems making things static just because we can.  The true test
> > of whether a symbol should be static or not is whether it forms part of
> > a sensible API or not.  For subsystems with a well defined API, this is
> > quite easy (although it hasn't prevented attempts to make even those
> > symbols static).  For some of our core subsystems (like the kernel API
> > in this case) it's much less well defined ... although we have a good
> > solid white area of things that must be part of the API and a good solid
> > black area of things that mustn't, we still have a large grey area which
> > things like kill_proc_info() fall into.
> > 
> > For any person who wants to make a static symbol exported, we force an
> > explanation out of them about what they're trying to do and why.  Might
> > I suggest we apply the same standard to anyone trying to make something
> > static?  i.e. they need to explain clearly why the symbol shouldn't be
> > part of any rational API.
> 
> And by how many percent will this bloat the kernel more in the long 
> term?

That's something I'm more than willing to live with if the tradeoff is
we think before making things static.

> > Thanks,
> > 
> > James
> > Date: Thu, 8 Feb 2007 22:33:21 -0500
> > From: Kyle McMartin <kyle@mcmartin.ca>
> > To: Matthew Wilcox <matthew@wil.cx>
> > Cc: Kyle McMartin <kyle@mcmartin.ca>,
> > 	parisc-linux <parisc-linux@lists.parisc-linux.org>
> > Subject: Re: [parisc-linux] 64-bit kernel broken.
> > 
> > On Thu, Feb 08, 2007 at 08:24:54PM -0700, Matthew Wilcox wrote:
> > > On Thu, Feb 08, 2007 at 07:43:14PM -0500, Kyle McMartin wrote:
> > > > > Right. This got inadvertantly reverted with some other stuff. Fixed in a
> > > > > second.
> > > > 
> > > > Fixed in 1736b4bbf2bbfebaad06114d569f3617517524d1.
> > > 
> > > make.err:/home/willy/nicol-2.6/arch/parisc/kernel/signal32.c:519:
> > > warning: implicit declaration of function 'kill_proc_info'
> > > make.err:(.text.compat_sys_rt_sigqueueinfo+0x80): undefined reference to
> > > `kill_proc_info'
> > > 
> > 
> > Guess who came home for Christmas
> > 
> > commit d3228a887cae75ef2b8b1211c31c539bef5a5698
> > Author: Adrian Bunk <bunk@stusta.de>
> > Date:   Wed Dec 6 20:38:22 2006 -0800
> > 
> >     [PATCH] make kernel/signal.c:kill_proc_info() static
> > 
> >     Signed-off-by: Adrian Bunk <bunk@stusta.de>
> >     Signed-off-by: Andrew Morton <akpm@osdl.org>
> >     Signed-off-by: Linus Torvalds <torvalds@osdl.org>
> 
> There are hundreds of such patches of mine that got included in Linus' 
> tree and that didn't cause problems. Besides making the kernel smaller, 
> they regularly find "it should have been used" bugs.

> In this one case, a patch that made something static that wasn't used 
> from other files during the over 9 years of it's existence clashes with 
> another patch that adds a user.

I'm really not that interested in the number of users ... that's only
one part of the measure of the relevance of an API.  However, if we're
actually going to revoke an API I'd like it to be done on the API's
merits (or lack of them) rather than simply whether there are any
current in-kernel users.

> Can we agree that it's not a usual case that the first user gets added 
> after more than 9 years?

Actually, the compat_rtsiginfo patch has been argued over and honed for
at least 3 years, so I'd say your statement isn't necessarily correct.
For some of its life, it was even in -mm.

> And making it global again when a user gets included isn't really that 
> hard.

The life of a non-x86 architecture maintainer is hard ... it involves
having lots of volunteers tirelessly chasing down things that broke
during the big two week merge frenzy.  It would be really helpful if
things like this didn't add to that burden.

James


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[parisc-linux] Re: Fw: Another problem with making things static

[Andrew Morton]

On Sat, 10 Feb 2007 19:47:16 -0600 James Bottomley <James.Bottomley@SteelEye.com> wrote:

> The life of a non-x86 architecture maintainer is hard ... it involves
> having lots of volunteers tirelessly chasing down things that broke
> during the big two week merge frenzy.

They should test -mm kernels and report any problems so those problems
don't get into mainline.

My attempt to build a working parisc cross-compiler failed, which doesn't help.
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Re: [parisc-linux] Re: Fw: Another problem with making things static

[Grant Grundler]

On Sat, Feb 10, 2007 at 08:19:11PM -0800, Andrew Morton wrote:
> On Sat, 10 Feb 2007 19:47:16 -0600 James Bottomley <James.Bottomley@SteelEye.com> wrote:
> 
> > The life of a non-x86 architecture maintainer is hard ... it involves
> > having lots of volunteers tirelessly chasing down things that broke
> > during the big two week merge frenzy.
> 
> They should test -mm kernels and report any problems so those problems
> don't get into mainline.

We probably could start doing that for some of the build flavors (32 bit).
Kyle/Willy have done a great job of reducing the diff between kernel.org
and parisc-linux.org trees.


> My attempt to build a working parisc cross-compiler failed, which doesn't help.

I appreciate your attempt to build parisc-linux.
Could you post which source tree and which build command line you used?

I'm pretty sure this can be fixed.
We've used cross compilers in the past so I know it's worked before.

thanks,
grant

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Re: [parisc-linux] Re: Fw: Another problem with making things static

[Andrew Morton]

On Sun, 11 Feb 2007 00:25:52 -0700 Grant Grundler <grundler@parisc-linux.org> wrote:

> > My attempt to build a working parisc cross-compiler failed, which doesn't help.
> 
> I appreciate your attempt to build parisc-linux.
> Could you post which source tree and which build command line you used?

It was maybe a year back - I spent a couple of days wrestling with
crosstool, ended up with _some_ useful crosscompilers (alpha, arm, i386,
ia64, m68k, mips, s390, sparc, sparc64 and x86_64).  parisc was one of the
ones which I gave up on but I do not have a record of what the problem was,
sorry.  It would have been a toolchain problem, not a kernel problem.

The most usual failure mode was simply inability to find any combination of
gcc/binutils/glibc which could be compiled.

> I'm pretty sure this can be fixed.
> We've used cross compilers in the past so I know it's worked before.

I say this a lot, but...  It is in the interests of arch maintainers to
help others to build cross-compilers.  If someone were to prepare a web
page (or even a script) which could be used to generate a kernel
cross-compilation environment for parisc then the parisc maintainers would
see a lot less breakage.

For one, I do allmodconfig on all architectures on all patches I get (and
that includes all the git trees).  If stuff breaks, the breaker gets to
hear about it, before it gets merged.

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Re: [parisc-linux] Re: Fw: Another problem with making things static

[Kyle McMartin]

On Sat, Feb 10, 2007 at 11:44:24PM -0800, Andrew Morton wrote:
> I say this a lot, but...  It is in the interests of arch maintainers to
> help others to build cross-compilers.  If someone were to prepare a web
> page (or even a script) which could be used to generate a kernel
> cross-compilation environment for parisc then the parisc maintainers would
> see a lot less breakage.
> 

Heh, I put this up last time you asked. :)

http://kyle.mcmartin.ca/hppa64-hp-linux-gcc-3.4.tar

Cheers,
	Kyle

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Re: [parisc-linux] Re: Fw: Another problem with making things static

[Thibaut VARENE]

On 2/11/07, Grant Grundler <grundler@parisc-linux.org> wrote:
> On Sat, Feb 10, 2007 at 11:44:24PM -0800, Andrew Morton wrote:

> > I say this a lot, but...  It is in the interests of arch maintainers to
> > help others to build cross-compilers.  If someone were to prepare a web
> > page (or even a script) which could be used to generate a kernel
> > cross-compilation environment for parisc then the parisc maintainers would
> > see a lot less breakage.
>
> Agreed.
> We have such a page:
>         http://www.parisc-linux.org/toolchain/PARISC-Linux-XC-HOWTO.html
>
> (link "Build XC" from www.p-l.o homepage)

This is unfortunately rather outdated... I wonder if it'd still work.
I've built a parisc xcompiler a while ago using
toolchain-source/tpkg-make, I'll try to do that again and make a
receipe available online.

HTH

-- 
Thibaut VARENE
http://www.parisc-linux.org/~varenet/
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Re: [parisc-linux] Re: Fw: Another problem with making things static

[Andrew Morton]

> On Sun, 11 Feb 2007 11:54:05 -0500 Kyle McMartin <kyle@mcmartin.ca> wrote:
> On Sat, Feb 10, 2007 at 11:44:24PM -0800, Andrew Morton wrote:
> > I say this a lot, but...  It is in the interests of arch maintainers to
> > help others to build cross-compilers.  If someone were to prepare a web
> > page (or even a script) which could be used to generate a kernel
> > cross-compilation environment for parisc then the parisc maintainers would
> > see a lot less breakage.
> > 
> 
> Heh, I put this up last time you asked. :)
> 
> http://kyle.mcmartin.ca/hppa64-hp-linux-gcc-3.4.tar
> 

Drat, I have no memory of that.   Thanks..
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[parisc-linux] Re: Fw: Another problem with making things static

[Adrian Bunk]

On Sat, Feb 10, 2007 at 07:47:16PM -0600, James Bottomley wrote:
> On Sat, 2007-02-10 at 22:43 +0100, Adrian Bunk wrote:
> > First of all thanks to Andrew for forwarding this email to me - it's 
> > otherwise a bit hard to defend against an email that doesn't reach me.
> 
> I think if you read the email you'll find it didn't actually attack you
> at all ... I was careful only to ask for a change of policy before
> accepting a patch that does nothing but make a function static.

Then let's call it "trying to establish rule forbidding something 
established without even informing the people whose actions you want to 
become forbidden".

> > >...
> > > 
> > > We're going to need this one reverting for parisc.  If you remember
> > > we've been trying to push a compat_sys_rt_sigqueueinfo but Andi keeps
> > > objecting, so it's remained local to our tree (an hence so has the
> > > symbol usage).
> > > 
> > > However, can we *please* stop this indiscriminate rampage through all
> > > the sybsystems making things static just because we can.  The true test
> > > of whether a symbol should be static or not is whether it forms part of
> > > a sensible API or not.  For subsystems with a well defined API, this is
> > > quite easy (although it hasn't prevented attempts to make even those
> > > symbols static).  For some of our core subsystems (like the kernel API
> > > in this case) it's much less well defined ... although we have a good
> > > solid white area of things that must be part of the API and a good solid
> > > black area of things that mustn't, we still have a large grey area which
> > > things like kill_proc_info() fall into.
> > > 
> > > For any person who wants to make a static symbol exported, we force an
> > > explanation out of them about what they're trying to do and why.  Might
> > > I suggest we apply the same standard to anyone trying to make something
> > > static?  i.e. they need to explain clearly why the symbol shouldn't be
> > > part of any rational API.
> > 
> > And by how many percent will this bloat the kernel more in the long 
> > term?
> 
> That's something I'm more than willing to live with if the tradeoff is
> we think before making things static.

The big kernel size increase is a reason why many people in the embedded 
world stay at kernel 2.4.

The fact that you can't get a 2.6 kernel as small as a 2.4 kernel is a 
serious regression. And the last time I checked it wasn't that there's 
some well-defined area where the size increase comes from - it's more or 
less evenly distributed between all not unmaintained parts of the 
kernel.

> > > Thanks,
> > > 
> > > James
> > > Date: Thu, 8 Feb 2007 22:33:21 -0500
> > > From: Kyle McMartin <kyle@mcmartin.ca>
> > > To: Matthew Wilcox <matthew@wil.cx>
> > > Cc: Kyle McMartin <kyle@mcmartin.ca>,
> > > 	parisc-linux <parisc-linux@lists.parisc-linux.org>
> > > Subject: Re: [parisc-linux] 64-bit kernel broken.
> > > 
> > > On Thu, Feb 08, 2007 at 08:24:54PM -0700, Matthew Wilcox wrote:
> > > > On Thu, Feb 08, 2007 at 07:43:14PM -0500, Kyle McMartin wrote:
> > > > > > Right. This got inadvertantly reverted with some other stuff. Fixed in a
> > > > > > second.
> > > > > 
> > > > > Fixed in 1736b4bbf2bbfebaad06114d569f3617517524d1.
> > > > 
> > > > make.err:/home/willy/nicol-2.6/arch/parisc/kernel/signal32.c:519:
> > > > warning: implicit declaration of function 'kill_proc_info'
> > > > make.err:(.text.compat_sys_rt_sigqueueinfo+0x80): undefined reference to
> > > > `kill_proc_info'
> > > > 
> > > 
> > > Guess who came home for Christmas
> > > 
> > > commit d3228a887cae75ef2b8b1211c31c539bef5a5698
> > > Author: Adrian Bunk <bunk@stusta.de>
> > > Date:   Wed Dec 6 20:38:22 2006 -0800
> > > 
> > >     [PATCH] make kernel/signal.c:kill_proc_info() static
> > > 
> > >     Signed-off-by: Adrian Bunk <bunk@stusta.de>
> > >     Signed-off-by: Andrew Morton <akpm@osdl.org>
> > >     Signed-off-by: Linus Torvalds <torvalds@osdl.org>
> > 
> > There are hundreds of such patches of mine that got included in Linus' 
> > tree and that didn't cause problems. Besides making the kernel smaller, 
> > they regularly find "it should have been used" bugs.
> 
> > In this one case, a patch that made something static that wasn't used 
> > from other files during the over 9 years of it's existence clashes with 
> > another patch that adds a user.
> 
> I'm really not that interested in the number of users ... that's only
> one part of the measure of the relevance of an API.  However, if we're
> actually going to revoke an API I'd like it to be done on the API's
> merits (or lack of them) rather than simply whether there are any
> current in-kernel users.
> 
> > Can we agree that it's not a usual case that the first user gets added 
> > after more than 9 years?
> 
> Actually, the compat_rtsiginfo patch has been argued over and honed for
> at least 3 years, so I'd say your statement isn't necessarily correct.
> For some of its life, it was even in -mm.
> 
> > And making it global again when a user gets included isn't really that 
> > hard.
> 
> The life of a non-x86 architecture maintainer is hard ... it involves
> having lots of volunteers tirelessly chasing down things that broke
> during the big two week merge frenzy.  It would be really helpful if
> things like this didn't add to that burden.

The change was not in -mm recently.

The simple rules:
- get your changes in -mm and
- test -mm kernels and scream if someone broke your architecture
would discover many problems before the 2 weeks merge window (and before 
problems hit Linus' tree).

This would also eliminate problems like the parisc defconfig not 
compiling in 2.6.20 due to the work_struct changes.

> James

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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[parisc-linux] Re: Fw: Another problem with making things static

[James Bottomley]

On Sun, 2007-02-11 at 08:35 +0100, Adrian Bunk wrote:
> On Sat, Feb 10, 2007 at 07:47:16PM -0600, James Bottomley wrote:
> > On Sat, 2007-02-10 at 22:43 +0100, Adrian Bunk wrote:
> > > First of all thanks to Andrew for forwarding this email to me - it's 
> > > otherwise a bit hard to defend against an email that doesn't reach me.
> > 
> > I think if you read the email you'll find it didn't actually attack you
> > at all ... I was careful only to ask for a change of policy before
> > accepting a patch that does nothing but make a function static.
> 
> Then let's call it "trying to establish rule forbidding something 
> established without even informing the people whose actions you want to 
> become forbidden".

I'm sorry, but I didn't realise you would be unable to come up with
justifications for API removal, and thus this would become an
insuperable bar to you.  The justification criterion was meant to be a
more objective way of judging whether some API should be revoked and it
seems to me, as a developer, to be a reasonable and not too onerous one.
As Andrew pointed out, for most of the driver and FS symbols the
justification is simply that this module isn't supposed to be exporting
an API at all.

James


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