[PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Tom Rini]

As per
http://lists.linuxtogo.org/pipermail/openembedded-core/2012-March/019772.html
a machine conf file should use '=' to set IMAGE_FSTYPES.

Signed-off-by: Tom Rini <trini@ti.com>
---
 meta/conf/machine/include/qemu.inc |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/meta/conf/machine/include/qemu.inc b/meta/conf/machine/include/qemu.inc
index 10ab76e..b613287 100644
--- a/meta/conf/machine/include/qemu.inc
+++ b/meta/conf/machine/include/qemu.inc
@@ -3,7 +3,7 @@ PREFERRED_PROVIDER_virtual/xserver ?= "xserver-kdrive"
 
 MACHINE_FEATURES = "apm alsa pcmcia bluetooth irda usbgadget screen"
 
-IMAGE_FSTYPES ?= "tar.bz2 ext3"
+IMAGE_FSTYPES = "tar.bz2 ext3"
 
 ROOT_FLASH_SIZE = "280"
 
-- 
1.7.0.4

Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Richard Purdie]

On Fri, 2012-03-23 at 10:35 -0700, Tom Rini wrote:
> As per
> http://lists.linuxtogo.org/pipermail/openembedded-core/2012-March/019772.html
> a machine conf file should use '=' to set IMAGE_FSTYPES.
> 
> Signed-off-by: Tom Rini <trini@ti.com>
> ---
>  meta/conf/machine/include/qemu.inc |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)

As someone pointed out, what I mentioned in that email sadly doesn't
work although it would be nice if they did. I suspect this is why we're
using += since:

> - The machine needs to say 'I need or support the following formats'

so the machine ensures those formats exist at a minimum:

IMAGE_FSTYPES += "xxxx"

> - The distro needs to say 'I always want format X'

so the distro can do:

IMAGE_FSTYPES += " yyy"

> - The user needs to say 'I know best, give me only format X'

This one is the problem case so the user has to use overrides:

IMAGE_FSTYPES_override = "X"

(where override can be MACHINE or forcevariable)

> - The user needs to say 'I know best, give me what you support + X'

IMAGE_FSTYPES += " X"


Whilst I think that is less than ideal since it forces use of overrides
in local.conf to override, changing the += in machine conf files doesn't
gain us much, it just breaks += in local.conf.

I'm open to other feedback though...

Cheers,

Richard

Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Tom Rini]

On Mon, Mar 26, 2012 at 10:15:13AM +0100, Richard Purdie wrote:
> On Fri, 2012-03-23 at 10:35 -0700, Tom Rini wrote:
> > As per
> > http://lists.linuxtogo.org/pipermail/openembedded-core/2012-March/019772.html
> > a machine conf file should use '=' to set IMAGE_FSTYPES.
> > 
> > Signed-off-by: Tom Rini <trini@ti.com>
> > ---
> >  meta/conf/machine/include/qemu.inc |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> As someone pointed out, what I mentioned in that email sadly doesn't
> work although it would be nice if they did. I suspect this is why we're
> using += since:

We aren't using += today.  We (openembedded-core) use ?=.  meta-intel
uses += and meta-ti is mixed (and I don't have meta-fsl-* handy).

> > - The machine needs to say 'I need or support the following formats'
> 
> so the machine ensures those formats exist at a minimum:
> 
> IMAGE_FSTYPES += "xxxx"
> 
> > - The distro needs to say 'I always want format X'
> 
> so the distro can do:
> 
> IMAGE_FSTYPES += " yyy"
> 
> > - The user needs to say 'I know best, give me only format X'
> 
> This one is the problem case so the user has to use overrides:
> 
> IMAGE_FSTYPES_override = "X"
> 
> (where override can be MACHINE or forcevariable)
> 
> > - The user needs to say 'I know best, give me what you support + X'
> 
> IMAGE_FSTYPES += " X"
> 
> 
> Whilst I think that is less than ideal since it forces use of overrides
> in local.conf to override, changing the += in machine conf files doesn't
> gain us much, it just breaks += in local.conf.
> 
> I'm open to other feedback though...

Well, I suggested ??= / ?= and posted some results from bitbake -e...

-- 
Tom

Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Richard Purdie]

On Mon, 2012-03-26 at 09:25 -0700, Tom Rini wrote:
> On Mon, Mar 26, 2012 at 10:15:13AM +0100, Richard Purdie wrote:
> > On Fri, 2012-03-23 at 10:35 -0700, Tom Rini wrote:
> > > As per
> > > http://lists.linuxtogo.org/pipermail/openembedded-core/2012-March/019772.html
> > > a machine conf file should use '=' to set IMAGE_FSTYPES.
> > > 
> > > Signed-off-by: Tom Rini <trini@ti.com>
> > > ---
> > >  meta/conf/machine/include/qemu.inc |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > As someone pointed out, what I mentioned in that email sadly doesn't
> > work although it would be nice if they did. I suspect this is why we're
> > using += since:
> 
> We aren't using += today.  We (openembedded-core) use ?=.  meta-intel
> uses += and meta-ti is mixed (and I don't have meta-fsl-* handy).
> 
> > > - The machine needs to say 'I need or support the following formats'
> > 
> > so the machine ensures those formats exist at a minimum:
> > 
> > IMAGE_FSTYPES += "xxxx"
> > 
> > > - The distro needs to say 'I always want format X'
> > 
> > so the distro can do:
> > 
> > IMAGE_FSTYPES += " yyy"
> > 
> > > - The user needs to say 'I know best, give me only format X'
> > 
> > This one is the problem case so the user has to use overrides:
> > 
> > IMAGE_FSTYPES_override = "X"
> > 
> > (where override can be MACHINE or forcevariable)
> > 
> > > - The user needs to say 'I know best, give me what you support + X'
> > 
> > IMAGE_FSTYPES += " X"
> > 
> > 
> > Whilst I think that is less than ideal since it forces use of overrides
> > in local.conf to override, changing the += in machine conf files doesn't
> > gain us much, it just breaks += in local.conf.
> > 
> > I'm open to other feedback though...
> 
> Well, I suggested ??= / ?= and posted some results from bitbake -e...

Ok. += plays out as above. I realise its not what is in qemu.inc, it is
used in meta-intel though which I looked at after qemu.inc and I guess
has confused me.

With ?= in machine.conf:

The user defined IMAGE_FSTYPES would override the machine ones. Distro
can still append to it. The downside is a user append would not work out
as expected.

So the question is which is the more user expected behaviour?

=+ makes overwriting IMAGE_FSTYPES hard

?= makes appending IMAGE_FSTYPES hard

I suspect a user is more likely to want to append than overwrite.
Getting an append to work with ?= is extremely non-obvious, even worse
syntax than the =+ overwriting case with overrides.

So bottom line, I'm tempted to recommend we use =+.

Further thoughts?

Cheers,

Richard

Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Tom Rini]

On Mon, Mar 26, 2012 at 05:56:16PM +0100, Richard Purdie wrote:
> On Mon, 2012-03-26 at 09:25 -0700, Tom Rini wrote:
> > On Mon, Mar 26, 2012 at 10:15:13AM +0100, Richard Purdie wrote:
> > > On Fri, 2012-03-23 at 10:35 -0700, Tom Rini wrote:
> > > > As per
> > > > http://lists.linuxtogo.org/pipermail/openembedded-core/2012-March/019772.html
> > > > a machine conf file should use '=' to set IMAGE_FSTYPES.
> > > > 
> > > > Signed-off-by: Tom Rini <trini@ti.com>
> > > > ---
> > > >  meta/conf/machine/include/qemu.inc |    2 +-
> > > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > 
> > > As someone pointed out, what I mentioned in that email sadly doesn't
> > > work although it would be nice if they did. I suspect this is why we're
> > > using += since:
> > 
> > We aren't using += today.  We (openembedded-core) use ?=.  meta-intel
> > uses += and meta-ti is mixed (and I don't have meta-fsl-* handy).
> > 
> > > > - The machine needs to say 'I need or support the following formats'
> > > 
> > > so the machine ensures those formats exist at a minimum:
> > > 
> > > IMAGE_FSTYPES += "xxxx"
> > > 
> > > > - The distro needs to say 'I always want format X'
> > > 
> > > so the distro can do:
> > > 
> > > IMAGE_FSTYPES += " yyy"
> > > 
> > > > - The user needs to say 'I know best, give me only format X'
> > > 
> > > This one is the problem case so the user has to use overrides:
> > > 
> > > IMAGE_FSTYPES_override = "X"
> > > 
> > > (where override can be MACHINE or forcevariable)
> > > 
> > > > - The user needs to say 'I know best, give me what you support + X'
> > > 
> > > IMAGE_FSTYPES += " X"
> > > 
> > > 
> > > Whilst I think that is less than ideal since it forces use of overrides
> > > in local.conf to override, changing the += in machine conf files doesn't
> > > gain us much, it just breaks += in local.conf.
> > > 
> > > I'm open to other feedback though...
> > 
> > Well, I suggested ??= / ?= and posted some results from bitbake -e...
> 
> Ok. += plays out as above. I realise its not what is in qemu.inc, it is
> used in meta-intel though which I looked at after qemu.inc and I guess
> has confused me.
> 
> With ?= in machine.conf:
> 
> The user defined IMAGE_FSTYPES would override the machine ones. Distro
> can still append to it. The downside is a user append would not work out
> as expected.
> 
> So the question is which is the more user expected behaviour?
> 
> =+ makes overwriting IMAGE_FSTYPES hard
> 
> ?= makes appending IMAGE_FSTYPES hard
> 
> I suspect a user is more likely to want to append than overwrite.
> Getting an append to work with ?= is extremely non-obvious, even worse
> syntax than the =+ overwriting case with overrides.
> 
> So bottom line, I'm tempted to recommend we use =+.

I think for the upcoming release, =+ is good enough and we can talk
about adding further variables after if it's still too complicated.  So,
now where's the repo that documenting these examples should go in?

-- 
Tom

Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Darren Hart]

On 03/26/2012 10:13 AM, Tom Rini wrote:

> 
> I think for the upcoming release, =+ is good enough and we can talk
> about adding further variables after if it's still too complicated.  So,
> now where's the repo that documenting these examples should go in?
> 

You want to talk to Scott Rifenbark, on CC.

-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel

Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Denys Dmytriyenko]

On Mon, Mar 26, 2012 at 10:13:59AM -0700, Tom Rini wrote:
> On Mon, Mar 26, 2012 at 05:56:16PM +0100, Richard Purdie wrote:
> > On Mon, 2012-03-26 at 09:25 -0700, Tom Rini wrote:
> > > On Mon, Mar 26, 2012 at 10:15:13AM +0100, Richard Purdie wrote:
> > > > On Fri, 2012-03-23 at 10:35 -0700, Tom Rini wrote:
> > > > > As per
> > > > > http://lists.linuxtogo.org/pipermail/openembedded-core/2012-March/019772.html
> > > > > a machine conf file should use '=' to set IMAGE_FSTYPES.
> > > > > 
> > > > > Signed-off-by: Tom Rini <trini@ti.com>
> > > > > ---
> > > > >  meta/conf/machine/include/qemu.inc |    2 +-
> > > > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > > 
> > > > As someone pointed out, what I mentioned in that email sadly doesn't
> > > > work although it would be nice if they did. I suspect this is why we're
> > > > using += since:
> > > 
> > > We aren't using += today.  We (openembedded-core) use ?=.  meta-intel
> > > uses += and meta-ti is mixed (and I don't have meta-fsl-* handy).
> > > 
> > > > > - The machine needs to say 'I need or support the following formats'
> > > > 
> > > > so the machine ensures those formats exist at a minimum:
> > > > 
> > > > IMAGE_FSTYPES += "xxxx"
> > > > 
> > > > > - The distro needs to say 'I always want format X'
> > > > 
> > > > so the distro can do:
> > > > 
> > > > IMAGE_FSTYPES += " yyy"
> > > > 
> > > > > - The user needs to say 'I know best, give me only format X'
> > > > 
> > > > This one is the problem case so the user has to use overrides:
> > > > 
> > > > IMAGE_FSTYPES_override = "X"
> > > > 
> > > > (where override can be MACHINE or forcevariable)
> > > > 
> > > > > - The user needs to say 'I know best, give me what you support + X'
> > > > 
> > > > IMAGE_FSTYPES += " X"
> > > > 
> > > > 
> > > > Whilst I think that is less than ideal since it forces use of overrides
> > > > in local.conf to override, changing the += in machine conf files doesn't
> > > > gain us much, it just breaks += in local.conf.
> > > > 
> > > > I'm open to other feedback though...
> > > 
> > > Well, I suggested ??= / ?= and posted some results from bitbake -e...
> > 
> > Ok. += plays out as above. I realise its not what is in qemu.inc, it is
> > used in meta-intel though which I looked at after qemu.inc and I guess
> > has confused me.
> > 
> > With ?= in machine.conf:
> > 
> > The user defined IMAGE_FSTYPES would override the machine ones. Distro
> > can still append to it. The downside is a user append would not work out
> > as expected.
> > 
> > So the question is which is the more user expected behaviour?
> > 
> > =+ makes overwriting IMAGE_FSTYPES hard
> > 
> > ?= makes appending IMAGE_FSTYPES hard
> > 
> > I suspect a user is more likely to want to append than overwrite.
> > Getting an append to work with ?= is extremely non-obvious, even worse
> > syntax than the =+ overwriting case with overrides.
> > 
> > So bottom line, I'm tempted to recommend we use =+.
> 
> I think for the upcoming release, =+ is good enough and we can talk
> about adding further variables after if it's still too complicated.  So,
> now where's the repo that documenting these examples should go in?

So, did we come full circle on this? :) Started here:
https://lists.yoctoproject.org/pipermail/meta-ti/2012-March/000779.html

I'm fine changing it for meta-ti, if we agree on a unified solution. Having an 
EXTRA/MACHINE var for that in the future might simplify things...

-- 
Denys

Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Denys Dmytriyenko]

On Mon, Mar 26, 2012 at 05:56:16PM +0100, Richard Purdie wrote:
> On Mon, 2012-03-26 at 09:25 -0700, Tom Rini wrote:
> > On Mon, Mar 26, 2012 at 10:15:13AM +0100, Richard Purdie wrote:
> > > On Fri, 2012-03-23 at 10:35 -0700, Tom Rini wrote:
> > > > As per
> > > > http://lists.linuxtogo.org/pipermail/openembedded-core/2012-March/019772.html
> > > > a machine conf file should use '=' to set IMAGE_FSTYPES.
> > > > 
> > > > Signed-off-by: Tom Rini <trini@ti.com>
> > > > ---
> > > >  meta/conf/machine/include/qemu.inc |    2 +-
> > > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > 
> > > As someone pointed out, what I mentioned in that email sadly doesn't
> > > work although it would be nice if they did. I suspect this is why we're
> > > using += since:
> > 
> > We aren't using += today.  We (openembedded-core) use ?=.  meta-intel
> > uses += and meta-ti is mixed (and I don't have meta-fsl-* handy).
> > 
> > > > - The machine needs to say 'I need or support the following formats'
> > > 
> > > so the machine ensures those formats exist at a minimum:
> > > 
> > > IMAGE_FSTYPES += "xxxx"
> > > 
> > > > - The distro needs to say 'I always want format X'
> > > 
> > > so the distro can do:
> > > 
> > > IMAGE_FSTYPES += " yyy"
> > > 
> > > > - The user needs to say 'I know best, give me only format X'
> > > 
> > > This one is the problem case so the user has to use overrides:
> > > 
> > > IMAGE_FSTYPES_override = "X"
> > > 
> > > (where override can be MACHINE or forcevariable)
> > > 
> > > > - The user needs to say 'I know best, give me what you support + X'
> > > 
> > > IMAGE_FSTYPES += " X"
> > > 
> > > 
> > > Whilst I think that is less than ideal since it forces use of overrides
> > > in local.conf to override, changing the += in machine conf files doesn't
> > > gain us much, it just breaks += in local.conf.
> > > 
> > > I'm open to other feedback though...
> > 
> > Well, I suggested ??= / ?= and posted some results from bitbake -e...
> 
> Ok. += plays out as above. I realise its not what is in qemu.inc, it is
> used in meta-intel though which I looked at after qemu.inc and I guess
> has confused me.
> 
> With ?= in machine.conf:
> 
> The user defined IMAGE_FSTYPES would override the machine ones. Distro
> can still append to it. The downside is a user append would not work out
> as expected.
> 
> So the question is which is the more user expected behaviour?
> 
> =+ makes overwriting IMAGE_FSTYPES hard
> 
> ?= makes appending IMAGE_FSTYPES hard
> 
> I suspect a user is more likely to want to append than overwrite.
> Getting an append to work with ?= is extremely non-obvious, even worse
> syntax than the =+ overwriting case with overrides.
> 
> So bottom line, I'm tempted to recommend we use =+.
> 
> Further thoughts?

Richard,

So, what is the subtle difference between += that we started with and =+ that 
you recommended at the end? I realize those are for append and prepend, but 
are they handled any different? Was your recommendation to use =+ at the end, 
instead of += that was used originally, based on some specifics? Thanks.

-- 
Denys

Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Richard Purdie]

On Wed, 2012-03-28 at 14:54 -0400, Denys Dmytriyenko wrote:
> On Mon, Mar 26, 2012 at 05:56:16PM +0100, Richard Purdie wrote:
> > On Mon, 2012-03-26 at 09:25 -0700, Tom Rini wrote:
> > > On Mon, Mar 26, 2012 at 10:15:13AM +0100, Richard Purdie wrote:
> > > > On Fri, 2012-03-23 at 10:35 -0700, Tom Rini wrote:
> > > > > As per
> > > > > http://lists.linuxtogo.org/pipermail/openembedded-core/2012-March/019772.html
> > > > > a machine conf file should use '=' to set IMAGE_FSTYPES.
> > > > > 
> > > > > Signed-off-by: Tom Rini <trini@ti.com>
> > > > > ---
> > > > >  meta/conf/machine/include/qemu.inc |    2 +-
> > > > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > > 
> > > > As someone pointed out, what I mentioned in that email sadly doesn't
> > > > work although it would be nice if they did. I suspect this is why we're
> > > > using += since:
> > > 
> > > We aren't using += today.  We (openembedded-core) use ?=.  meta-intel
> > > uses += and meta-ti is mixed (and I don't have meta-fsl-* handy).
> > > 
> > > > > - The machine needs to say 'I need or support the following formats'
> > > > 
> > > > so the machine ensures those formats exist at a minimum:
> > > > 
> > > > IMAGE_FSTYPES += "xxxx"
> > > > 
> > > > > - The distro needs to say 'I always want format X'
> > > > 
> > > > so the distro can do:
> > > > 
> > > > IMAGE_FSTYPES += " yyy"
> > > > 
> > > > > - The user needs to say 'I know best, give me only format X'
> > > > 
> > > > This one is the problem case so the user has to use overrides:
> > > > 
> > > > IMAGE_FSTYPES_override = "X"
> > > > 
> > > > (where override can be MACHINE or forcevariable)
> > > > 
> > > > > - The user needs to say 'I know best, give me what you support + X'
> > > > 
> > > > IMAGE_FSTYPES += " X"
> > > > 
> > > > 
> > > > Whilst I think that is less than ideal since it forces use of overrides
> > > > in local.conf to override, changing the += in machine conf files doesn't
> > > > gain us much, it just breaks += in local.conf.
> > > > 
> > > > I'm open to other feedback though...
> > > 
> > > Well, I suggested ??= / ?= and posted some results from bitbake -e...
> > 
> > Ok. += plays out as above. I realise its not what is in qemu.inc, it is
> > used in meta-intel though which I looked at after qemu.inc and I guess
> > has confused me.
> > 
> > With ?= in machine.conf:
> > 
> > The user defined IMAGE_FSTYPES would override the machine ones. Distro
> > can still append to it. The downside is a user append would not work out
> > as expected.
> > 
> > So the question is which is the more user expected behaviour?
> > 
> > =+ makes overwriting IMAGE_FSTYPES hard
> > 
> > ?= makes appending IMAGE_FSTYPES hard
> > 
> > I suspect a user is more likely to want to append than overwrite.
> > Getting an append to work with ?= is extremely non-obvious, even worse
> > syntax than the =+ overwriting case with overrides.
> > 
> > So bottom line, I'm tempted to recommend we use =+.
> > 
> > Further thoughts?
> 
> Richard,
> 
> So, what is the subtle difference between += that we started with and =+ that 
> you recommended at the end? I realize those are for append and prepend, but 
> are they handled any different? Was your recommendation to use =+ at the end, 
> instead of += that was used originally, based on some specifics? Thanks.

I'm using += and =+ interchangeably. The contrast was with ?= which I
argued against. Order in this case doesn't matter and I have no
preference over += or =+, it simply doesn't matter.

Cheers,

Richard

Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Tom Rini]

On Wed, Mar 28, 2012 at 10:11:44PM +0100, Richard Purdie wrote:
> On Wed, 2012-03-28 at 14:54 -0400, Denys Dmytriyenko wrote:
> > On Mon, Mar 26, 2012 at 05:56:16PM +0100, Richard Purdie wrote:
> > > On Mon, 2012-03-26 at 09:25 -0700, Tom Rini wrote:
> > > > On Mon, Mar 26, 2012 at 10:15:13AM +0100, Richard Purdie wrote:
> > > > > On Fri, 2012-03-23 at 10:35 -0700, Tom Rini wrote:
> > > > > > As per
> > > > > > http://lists.linuxtogo.org/pipermail/openembedded-core/2012-March/019772.html
> > > > > > a machine conf file should use '=' to set IMAGE_FSTYPES.
> > > > > > 
> > > > > > Signed-off-by: Tom Rini <trini@ti.com>
> > > > > > ---
> > > > > >  meta/conf/machine/include/qemu.inc |    2 +-
> > > > > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > > > 
> > > > > As someone pointed out, what I mentioned in that email sadly doesn't
> > > > > work although it would be nice if they did. I suspect this is why we're
> > > > > using += since:
> > > > 
> > > > We aren't using += today.  We (openembedded-core) use ?=.  meta-intel
> > > > uses += and meta-ti is mixed (and I don't have meta-fsl-* handy).
> > > > 
> > > > > > - The machine needs to say 'I need or support the following formats'
> > > > > 
> > > > > so the machine ensures those formats exist at a minimum:
> > > > > 
> > > > > IMAGE_FSTYPES += "xxxx"
> > > > > 
> > > > > > - The distro needs to say 'I always want format X'
> > > > > 
> > > > > so the distro can do:
> > > > > 
> > > > > IMAGE_FSTYPES += " yyy"
> > > > > 
> > > > > > - The user needs to say 'I know best, give me only format X'
> > > > > 
> > > > > This one is the problem case so the user has to use overrides:
> > > > > 
> > > > > IMAGE_FSTYPES_override = "X"
> > > > > 
> > > > > (where override can be MACHINE or forcevariable)
> > > > > 
> > > > > > - The user needs to say 'I know best, give me what you support + X'
> > > > > 
> > > > > IMAGE_FSTYPES += " X"
> > > > > 
> > > > > 
> > > > > Whilst I think that is less than ideal since it forces use of overrides
> > > > > in local.conf to override, changing the += in machine conf files doesn't
> > > > > gain us much, it just breaks += in local.conf.
> > > > > 
> > > > > I'm open to other feedback though...
> > > > 
> > > > Well, I suggested ??= / ?= and posted some results from bitbake -e...
> > > 
> > > Ok. += plays out as above. I realise its not what is in qemu.inc, it is
> > > used in meta-intel though which I looked at after qemu.inc and I guess
> > > has confused me.
> > > 
> > > With ?= in machine.conf:
> > > 
> > > The user defined IMAGE_FSTYPES would override the machine ones. Distro
> > > can still append to it. The downside is a user append would not work out
> > > as expected.
> > > 
> > > So the question is which is the more user expected behaviour?
> > > 
> > > =+ makes overwriting IMAGE_FSTYPES hard
> > > 
> > > ?= makes appending IMAGE_FSTYPES hard
> > > 
> > > I suspect a user is more likely to want to append than overwrite.
> > > Getting an append to work with ?= is extremely non-obvious, even worse
> > > syntax than the =+ overwriting case with overrides.
> > > 
> > > So bottom line, I'm tempted to recommend we use =+.
> > > 
> > > Further thoughts?
> > 
> > Richard,
> > 
> > So, what is the subtle difference between += that we started with and =+ that 
> > you recommended at the end? I realize those are for append and prepend, but 
> > are they handled any different? Was your recommendation to use =+ at the end, 
> > instead of += that was used originally, based on some specifics? Thanks.
> 
> I'm using += and =+ interchangeably. The contrast was with ?= which I
> argued against. Order in this case doesn't matter and I have no
> preference over += or =+, it simply doesn't matter.

So I guess I'll spin everything one more time and drop the meta-intel
version and we'll just use += since that's the common one.

-- 
Tom

Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Richard Purdie]

On Wed, 2012-03-28 at 16:29 -0700, Tom Rini wrote:
> On Wed, Mar 28, 2012 at 10:11:44PM +0100, Richard Purdie wrote:
> > On Wed, 2012-03-28 at 14:54 -0400, Denys Dmytriyenko wrote:
> > > On Mon, Mar 26, 2012 at 05:56:16PM +0100, Richard Purdie wrote:
> > > > On Mon, 2012-03-26 at 09:25 -0700, Tom Rini wrote:
> > > So, what is the subtle difference between += that we started with and =+ that 
> > > you recommended at the end? I realize those are for append and prepend, but 
> > > are they handled any different? Was your recommendation to use =+ at the end, 
> > > instead of += that was used originally, based on some specifics? Thanks.
> > 
> > I'm using += and =+ interchangeably. The contrast was with ?= which I
> > argued against. Order in this case doesn't matter and I have no
> > preference over += or =+, it simply doesn't matter.
> 
> So I guess I'll spin everything one more time and drop the meta-intel
> version and we'll just use += since that's the common one.

Sounds good. Sorry about the churn on this one, I thought it was clear
+= and =+ were equivalent in this context.

Cheers,

Richard