libfdt shared library

libfdt shared library

[Josh Boyer]

Hi All,

There's been a bug open for a while to get a libfdt shared
library built in Fedora:

http://bugzilla.redhat.com/show_bug.cgi?id=443882

This would have benefits for things like qemu and other
applications that don't really need to statically link the
libfdt.a into the binary itself.

The reason we're waiting is because it would be best to
have the upstream project define the soname and versioning
that would be used.  As mentioned in the bug, it could be
as simple as using the base dtc version that it is split
from, but for commonality reasons we'd want to settle on
a single way to do it.  That belongs upstream.

So this is my plea for coming up with a solution.  I can
code up patches, but I thought some discussion would be
proper first.

josh

Re: libfdt shared library

[David Gibson]

On Tue, Nov 18, 2008 at 12:47:52PM -0500, Josh Boyer wrote:
> Hi All,
> 
> There's been a bug open for a while to get a libfdt shared
> library built in Fedora:
> 
> http://bugzilla.redhat.com/show_bug.cgi?id=443882
> 
> This would have benefits for things like qemu and other
> applications that don't really need to statically link the
> libfdt.a into the binary itself.
> 
> The reason we're waiting is because it would be best to
> have the upstream project define the soname and versioning
> that would be used.  As mentioned in the bug, it could be
> as simple as using the base dtc version that it is split
> from, but for commonality reasons we'd want to settle on
> a single way to do it.  That belongs upstream.
> 
> So this is my plea for coming up with a solution.  I can
> code up patches, but I thought some discussion would be
> proper first.

Um.. well.. first for your immediate issue of getting libfdt into
Fedora, can I suggest you just use the static library.  Sure, a shared
library would be nice, but libfdt is sufficiently small that I don't
think it's that bad to link statically with it.

Longer term it would be nice to build a shared object of libfdt with
the rest.  Soname is pretty easy to come up with, but we should
possibly also do symbol versioning for further security against future
changes breaking things.  My current philosophy is to try very hard to
keep the libfdt API stable, but not try particularly hard to keep the
ABI stable.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

Re: libfdt shared library

[Josh Boyer]

On Wed, 19 Nov 2008 14:38:19 +1100
David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org> wrote:

> On Tue, Nov 18, 2008 at 12:47:52PM -0500, Josh Boyer wrote:
> > Hi All,
> > 
> > There's been a bug open for a while to get a libfdt shared
> > library built in Fedora:
> > 
> > http://bugzilla.redhat.com/show_bug.cgi?id=443882
> > 
> > This would have benefits for things like qemu and other
> > applications that don't really need to statically link the
> > libfdt.a into the binary itself.
> > 
> > The reason we're waiting is because it would be best to
> > have the upstream project define the soname and versioning
> > that would be used.  As mentioned in the bug, it could be
> > as simple as using the base dtc version that it is split
> > from, but for commonality reasons we'd want to settle on
> > a single way to do it.  That belongs upstream.
> > 
> > So this is my plea for coming up with a solution.  I can
> > code up patches, but I thought some discussion would be
> > proper first.
> 
> Um.. well.. first for your immediate issue of getting libfdt into
> Fedora, can I suggest you just use the static library.  Sure, a shared
> library would be nice, but libfdt is sufficiently small that I don't
> think it's that bad to link statically with it.

It's sort-of already in Fedora.  At least the source is in DTC.
However, Fedora has rules about static libraries and when they can be
provided.  I asked about this in the above bug report, but really what
we're after is the shared version.

> Longer term it would be nice to build a shared object of libfdt with
> the rest.  Soname is pretty easy to come up with, but we should
> possibly also do symbol versioning for further security against future
> changes breaking things.  My current philosophy is to try very hard to
> keep the libfdt API stable, but not try particularly hard to keep the
> ABI stable.

OK, fine by me.  Do you want to continue on with that, or should I look
at doing something along those lines?  The symbol versioning part would
take me a bit.

josh

Re: libfdt shared library

[David Gibson]

On Wed, Nov 19, 2008 at 06:25:06AM -0500, Josh Boyer wrote:
> On Wed, 19 Nov 2008 14:38:19 +1100
> David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org> wrote:
> 
> > On Tue, Nov 18, 2008 at 12:47:52PM -0500, Josh Boyer wrote:
> > > Hi All,
> > > 
> > > There's been a bug open for a while to get a libfdt shared
> > > library built in Fedora:
> > > 
> > > http://bugzilla.redhat.com/show_bug.cgi?id=443882
> > > 
> > > This would have benefits for things like qemu and other
> > > applications that don't really need to statically link the
> > > libfdt.a into the binary itself.
> > > 
> > > The reason we're waiting is because it would be best to
> > > have the upstream project define the soname and versioning
> > > that would be used.  As mentioned in the bug, it could be
> > > as simple as using the base dtc version that it is split
> > > from, but for commonality reasons we'd want to settle on
> > > a single way to do it.  That belongs upstream.
> > > 
> > > So this is my plea for coming up with a solution.  I can
> > > code up patches, but I thought some discussion would be
> > > proper first.
> > 
> > Um.. well.. first for your immediate issue of getting libfdt into
> > Fedora, can I suggest you just use the static library.  Sure, a shared
> > library would be nice, but libfdt is sufficiently small that I don't
> > think it's that bad to link statically with it.
> 
> It's sort-of already in Fedora.  At least the source is in DTC.
> However, Fedora has rules about static libraries and when they can be
> provided.  I asked about this in the above bug report, but really what
> we're after is the shared version.

Heh, alright.

> > Longer term it would be nice to build a shared object of libfdt with
> > the rest.  Soname is pretty easy to come up with, but we should
> > possibly also do symbol versioning for further security against future
> > changes breaking things.  My current philosophy is to try very hard to
> > keep the libfdt API stable, but not try particularly hard to keep the
> > ABI stable.
> 
> OK, fine by me.  Do you want to continue on with that, or should I look
> at doing something along those lines?  The symbol versioning part would
> take me a bit.

Uh.. doesn't look like I'm going to have time for this any time soon.
So you might as well.  Maybe look at libhugetlbfs for an example of
the symbol versioning - it has a somewhat similar makefile setup, and
is reasonable simple.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson