[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Lothar Felten]

Patch dtc to accept libfdt include guards with and without leading underscore.
A compiler warning is added to notify the user.

Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
---
 ...de-guards-for-older-kernel-u-boot-sources.patch | 42 ++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch

diff --git a/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
new file mode 100644
index 0000000000..40cb0bdb2a
--- /dev/null
+++ b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
@@ -0,0 +1,42 @@
+From b1f8b84489c96465b63485b884238b61d31ca84d Mon Sep 17 00:00:00 2001
+From: Lothar Felten <lothar.felten@gmail.com>
+Date: Mon, 8 Oct 2018 13:29:44 +0200
+Subject: [PATCH 1/1] Fix include guards for older kernel/u-boot sources
+
+Linux kernels before 4.17 and U-Boot versions before 2018.07 use libfdt include guards with leading underscores.
+Those have been removed in dtc-1.4.7.
+This patch handles both include guard types and allows the compilation of older Linux kernel and u-boot sources.
+
+Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
+---
+ libfdt/libfdt.h     | 4 ++++
+ libfdt/libfdt_env.h | 4 ++++
+ 2 files changed, 8 insertions(+)
+
+diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
+index 830b77e..bef4566 100644
+--- a/libfdt/libfdt.h
++++ b/libfdt/libfdt.h
+@@ -1,3 +1,7 @@
++#ifdef _LIBFDT_H
++#warning "Please consider updating your kernel and/or u-boot version"
++#define LIBFDT_H
++#endif
+ #ifndef LIBFDT_H
+ #define LIBFDT_H
+ /*
+diff --git a/libfdt/libfdt_env.h b/libfdt/libfdt_env.h
+index eb20538..6a61e6a 100644
+--- a/libfdt/libfdt_env.h
++++ b/libfdt/libfdt_env.h
+@@ -1,3 +1,7 @@
++#ifdef _LIBFDT_ENV_H
++#warning "Please consider updating your kernel and/or u-boot version"
++#define LIBFDT_ENV_H
++#endif
+ #ifndef LIBFDT_ENV_H
+ #define LIBFDT_ENV_H
+ /*
+-- 
+2.11.0
+
-- 
2.11.0

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Matthew Weber]

Lothar,


On Mon, Oct 8, 2018 at 6:52 AM Lothar Felten <lothar.felten@gmail.com> wrote:
>
> Patch dtc to accept libfdt include guards with and without leading underscore.
> A compiler warning is added to notify the user.
>
> Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
> ---
>  ...de-guards-for-older-kernel-u-boot-sources.patch | 42 ++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
>  create mode 100644 package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
>
> diff --git a/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
> new file mode 100644
> index 0000000000..40cb0bdb2a
> --- /dev/null
> +++ b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
> @@ -0,0 +1,42 @@
> +From b1f8b84489c96465b63485b884238b61d31ca84d Mon Sep 17 00:00:00 2001
> +From: Lothar Felten <lothar.felten@gmail.com>
> +Date: Mon, 8 Oct 2018 13:29:44 +0200
> +Subject: [PATCH 1/1] Fix include guards for older kernel/u-boot sources
> +
> +Linux kernels before 4.17 and U-Boot versions before 2018.07 use libfdt include guards with leading underscores.
> +Those have been removed in dtc-1.4.7.

Is there an reference that could be listed to either
1) A upstream mailinglist/patchwork link that proposes adding this patch
2) If the patch below can't be upstreamed, a reference to the commit
that is reverting this support you're adding back in and maybe a
summary of why the backwards compatibility isn't' accepted.

Matt

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Lothar Felten]

Hello Matthew,

> Lothar,
> 
> 
> On Mon, Oct 8, 2018 at 6:52 AM Lothar Felten <lothar.felten@gmail.com
> > wrote:
> > 
> > Patch dtc to accept libfdt include guards with and without leading
> > underscore.
> > A compiler warning is added to notify the user.
> > 
> > Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
> > ---
> > ?...de-guards-for-older-kernel-u-boot-sources.patch | 42
> > ++++++++++++++++++++++
> > ?1 file changed, 42 insertions(+)
> > ?create mode 100644 package/dtc/0001-Fix-include-guards-for-older-
> > kernel-u-boot-sources.patch
> > 
> > diff --git a/package/dtc/0001-Fix-include-guards-for-older-kernel-
> > u-boot-sources.patch b/package/dtc/0001-Fix-include-guards-for-
> > older-kernel-u-boot-sources.patch
> > new file mode 100644
> > index 0000000000..40cb0bdb2a
> > --- /dev/null
> > +++ b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-
> > sources.patch
> > @@ -0,0 +1,42 @@
> > +From b1f8b84489c96465b63485b884238b61d31ca84d Mon Sep 17 00:00:00
> > 2001
> > +From: Lothar Felten <lothar.felten@gmail.com>
> > +Date: Mon, 8 Oct 2018 13:29:44 +0200
> > +Subject: [PATCH 1/1] Fix include guards for older kernel/u-boot
> > sources
> > +
> > +Linux kernels before 4.17 and U-Boot versions before 2018.07 use
> > libfdt include guards with leading underscores.
> > +Those have been removed in dtc-1.4.7.
> 
> Is there an reference that could be listed to either
> 1) A upstream mailinglist/patchwork link that proposes adding this
> patch
> 2) If the patch below can't be upstreamed, a reference to the commit
> that is reverting this support you're adding back in and maybe a
> summary of why the backwards compatibility isn't' accepted.

This patch is a temporary fix for this issue:
https://git.buildroot.org/buildroot/tree/CHANGES#n35

It does not fix any bug, just an incompatibility of a new dtc and older
Linux kernels / u-boot loaders.

Once all Linux kernel versions are >=4.17 and u-boot versions are
>=2018.07 this patch is no longer required: they will all use the
include guard without underscore.

I could also patch the beaglebone kernel, but other targets have the 
same issue (e.g. bananapi_m1).

> 
> Matt

Lothar

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Arnout Vandecappelle]

On 8/10/18 15:10, Matthew Weber wrote:
> Lothar,
> 
> 
> On Mon, Oct 8, 2018 at 6:52 AM Lothar Felten <lothar.felten@gmail.com> wrote:
>>
>> Patch dtc to accept libfdt include guards with and without leading underscore.
>> A compiler warning is added to notify the user.
>>
>> Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
>> ---
>>  ...de-guards-for-older-kernel-u-boot-sources.patch | 42 ++++++++++++++++++++++
>>  1 file changed, 42 insertions(+)
>>  create mode 100644 package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
>>
>> diff --git a/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
>> new file mode 100644
>> index 0000000000..40cb0bdb2a
>> --- /dev/null
>> +++ b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
>> @@ -0,0 +1,42 @@
>> +From b1f8b84489c96465b63485b884238b61d31ca84d Mon Sep 17 00:00:00 2001
>> +From: Lothar Felten <lothar.felten@gmail.com>
>> +Date: Mon, 8 Oct 2018 13:29:44 +0200
>> +Subject: [PATCH 1/1] Fix include guards for older kernel/u-boot sources
>> +
>> +Linux kernels before 4.17 and U-Boot versions before 2018.07 use libfdt include guards with leading underscores.
>> +Those have been removed in dtc-1.4.7.
> 
> Is there an reference that could be listed to either
> 1) A upstream mailinglist/patchwork link that proposes adding this patch
> 2) If the patch below can't be upstreamed, a reference to the commit
> that is reverting this support you're adding back in and maybe a
> summary of why the backwards compatibility isn't' accepted.

 I expect that it is not acceptable for upstream because this is only needed
when you include *both* libfdt.h from dtc and the one from the local copy, which
is clearly completely bogus. It happens due to bugs in the build system of
u-boot and of the beaglebone fork of the kernel (AFAIK it doesn't happen with
any upstream kernel version).

 So "fixing" it like this is really a workaround for broken u-boot/kernel that
is only applicable to Buildroot, because we have no easy way to generically
apply patches to u-boot/kernel while we can easily do it for dtc.

 Lothar, if you agree with the above analysis, could you include that in the
commit message of 0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch ?

 Also:

- please wrap the commit message of the patch itself at 72 columns as well;

- please number it properly, i.e. it should have number 2 instead of 1. Patch 1
was committed almost a month ago...

 Regards,
 Arnout

-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Yann E. MORIN]

Lothar, All,

On 2018-10-08 13:51 +0200, Lothar Felten spake thusly:
> Patch dtc to accept libfdt include guards with and without leading underscore.
> A compiler warning is added to notify the user.

Please, do not add the warning. We should be as transparent as possible
when we add such workarounds.

It is not unseen that a configure script parses the output of gcc to
detect stuff, and expect the output to be either empty or a specific
regexp; adding this warning would break that.

Otherwise, the patch is simple enough, and looks OKish as a workaround.

Maybe we could suggest upstream to carry such a patch? And then, it
would be their call to add the warning or not.

Regards,
Yann E. MORIN.

> Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
> ---
>  ...de-guards-for-older-kernel-u-boot-sources.patch | 42 ++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
>  create mode 100644 package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
> 
> diff --git a/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
> new file mode 100644
> index 0000000000..40cb0bdb2a
> --- /dev/null
> +++ b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
> @@ -0,0 +1,42 @@
> +From b1f8b84489c96465b63485b884238b61d31ca84d Mon Sep 17 00:00:00 2001
> +From: Lothar Felten <lothar.felten@gmail.com>
> +Date: Mon, 8 Oct 2018 13:29:44 +0200
> +Subject: [PATCH 1/1] Fix include guards for older kernel/u-boot sources
> +
> +Linux kernels before 4.17 and U-Boot versions before 2018.07 use libfdt include guards with leading underscores.
> +Those have been removed in dtc-1.4.7.
> +This patch handles both include guard types and allows the compilation of older Linux kernel and u-boot sources.
> +
> +Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
> +---
> + libfdt/libfdt.h     | 4 ++++
> + libfdt/libfdt_env.h | 4 ++++
> + 2 files changed, 8 insertions(+)
> +
> +diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> +index 830b77e..bef4566 100644
> +--- a/libfdt/libfdt.h
> ++++ b/libfdt/libfdt.h
> +@@ -1,3 +1,7 @@
> ++#ifdef _LIBFDT_H
> ++#warning "Please consider updating your kernel and/or u-boot version"
> ++#define LIBFDT_H
> ++#endif
> + #ifndef LIBFDT_H
> + #define LIBFDT_H
> + /*
> +diff --git a/libfdt/libfdt_env.h b/libfdt/libfdt_env.h
> +index eb20538..6a61e6a 100644
> +--- a/libfdt/libfdt_env.h
> ++++ b/libfdt/libfdt_env.h
> +@@ -1,3 +1,7 @@
> ++#ifdef _LIBFDT_ENV_H
> ++#warning "Please consider updating your kernel and/or u-boot version"
> ++#define LIBFDT_ENV_H
> ++#endif
> + #ifndef LIBFDT_ENV_H
> + #define LIBFDT_ENV_H
> + /*
> +-- 
> +2.11.0
> +
> -- 
> 2.11.0
> 

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Thomas Petazzoni]

Hello,

On Mon,  8 Oct 2018 13:51:46 +0200, Lothar Felten wrote:
> Patch dtc to accept libfdt include guards with and without leading underscore.
> A compiler warning is added to notify the user.
> 
> Signed-off-by: Lothar Felten <lothar.felten@gmail.com>

So I guess this would fix the problem when host-dtc is built before
some old Linux/U-Boot version.

However, I suppose it doesn't fix the problem when you have a
recent version of libfdt installed on your system (through your
distribution), that doesn't play well with those older Linux/U-Boot
versions. Correct ?

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Yann E. MORIN]

Thomas, All,

On 2018-10-08 18:02 +0200, Thomas Petazzoni spake thusly:
> On Mon,  8 Oct 2018 13:51:46 +0200, Lothar Felten wrote:
> > Patch dtc to accept libfdt include guards with and without leading underscore.
> > A compiler warning is added to notify the user.
> > 
> > Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
> 
> So I guess this would fix the problem when host-dtc is built before
> some old Linux/U-Boot version.
> 
> However, I suppose it doesn't fix the problem when you have a
> recent version of libfdt installed on your system (through your
> distribution), that doesn't play well with those older Linux/U-Boot
> versions. Correct ?

Probably not, indeed, but that is still better (IMHO) than the few hacks
we already tried with -isystem or the likes, which do not really work
either...

Regards,
Yann E. MORIN.

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Arnout Vandecappelle]

On 8/10/18 18:32, Yann E. MORIN wrote:
> Thomas, All,
> 
> On 2018-10-08 18:02 +0200, Thomas Petazzoni spake thusly:
>> On Mon,  8 Oct 2018 13:51:46 +0200, Lothar Felten wrote:
>>> Patch dtc to accept libfdt include guards with and without leading underscore.
>>> A compiler warning is added to notify the user.
>>>
>>> Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
>>
>> So I guess this would fix the problem when host-dtc is built before
>> some old Linux/U-Boot version.
>>
>> However, I suppose it doesn't fix the problem when you have a
>> recent version of libfdt installed on your system (through your
>> distribution), that doesn't play well with those older Linux/U-Boot
>> versions. Correct ?
> 
> Probably not, indeed, but that is still better (IMHO) than the few hacks
> we already tried with -isystem or the likes, which do not really work
> either...

 As far as we tested it, [1] *does* really work.

 However, it doesn't fix the issue for U-Boot because there the build system is
really broken: it misses the necessary -I to include the internal libfdt.h, so
only the fdt_host.h that explicitly includes ../include/libfdt.h uses the
internal one; other includes use <libfdt.h> so the host-provided one. So U-Boot
before v2018.03 is just broken beyond repair.

 Note that this patch will solve the problem for the time being. However, as
soon as dtc's libfdt.h contains some declaration that is incompatible with the
one in U-Boot pre-2018.03, U-Boot will break again.

 A possibly more fundamental workaround for U-Boot could be to pass
-I$(UBOOT_SRCDIR)/include in HOSTCC, but that has the potential to introduce
additional breakage...

 Regards,
 Arnout


[1] http://patchwork.ozlabs.org/patch/964474/

-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Yann E. MORIN]

Arnout, All,

On 2018-10-08 21:21 +0200, Arnout Vandecappelle spake thusly:
> On 8/10/18 18:32, Yann E. MORIN wrote:
> > On 2018-10-08 18:02 +0200, Thomas Petazzoni spake thusly:
> >> However, I suppose it doesn't fix the problem when you have a
> >> recent version of libfdt installed on your system (through your
> >> distribution), that doesn't play well with those older Linux/U-Boot
> >> versions. Correct ?
> > Probably not, indeed, but that is still better (IMHO) than the few hacks
> > we already tried with -isystem or the likes, which do not really work
> > either...
>  As far as we tested it, [1] *does* really work.
> [1] http://patchwork.ozlabs.org/patch/964474/

No it does not. Please see commit 6f8162cf8c1abef7e0a4771fe0d6b26a28f5c2b6
which got reverted by 255b6f80d395ef048f46cfcf75dba690c56af657, and which
was supposed to fix a very similar issue...

Regards,
Yann E. MORIN.

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 223 225 172 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Lothar Felten]

Hello,

On Mon, 2018-10-08 at 18:02 +0200, Thomas Petazzoni wrote:
> Hello,
> 
> On Mon,??8 Oct 2018 13:51:46 +0200, Lothar Felten wrote:
> > Patch dtc to accept libfdt include guards with and without leading
> > underscore.
> > A compiler warning is added to notify the user.
> > 
> > Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
> 
> So I guess this would fix the problem when host-dtc is built before
> some old Linux/U-Boot version.
> 
> However, I suppose it doesn't fix the problem when you have a
> recent version of libfdt installed on your system (through your
> distribution), that doesn't play well with those older Linux/U-Boot
> versions. Correct ?

Maybe. I have no libfdt headers on my host. This patch fixes the
failures caused by host-dtc (ver 1.4.7) and older u-boot or kernel
versions.
Building an older kernel without libfdt headers on the host works (it
uses the libfdt from the kernel) as long as host-dtc is not selected.

Just creating a /usr/include/[libfdt/]libfdt_env.h with a single #error
does not  prevent a u-boot-2016.09.01 build, so I suppose the include
paths are ok.

I expect this to be a temporary fix until all targets use a recent u-
boot and kernel.


> Thomas

Lothar

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Arnout Vandecappelle]

On 8/10/18 21:31, Yann E. MORIN wrote:
> Arnout, All,
> 
> On 2018-10-08 21:21 +0200, Arnout Vandecappelle spake thusly:
>> On 8/10/18 18:32, Yann E. MORIN wrote:
>>> On 2018-10-08 18:02 +0200, Thomas Petazzoni spake thusly:
>>>> However, I suppose it doesn't fix the problem when you have a
>>>> recent version of libfdt installed on your system (through your
>>>> distribution), that doesn't play well with those older Linux/U-Boot
>>>> versions. Correct ?
>>> Probably not, indeed, but that is still better (IMHO) than the few hacks
>>> we already tried with -isystem or the likes, which do not really work
>>> either...
>>  As far as we tested it, [1] *does* really work.
>> [1] http://patchwork.ozlabs.org/patch/964474/
> 
> No it does not. Please see commit 6f8162cf8c1abef7e0a4771fe0d6b26a28f5c2b6
> which got reverted by 255b6f80d395ef048f46cfcf75dba690c56af657, and which
> was supposed to fix a very similar issue...

 Ah, good that you saw this.

 Unfortunately 255b6f80d just says that there were too many issues.

 So I went back to the mail archives, and as far as I can see the only issue was
with python. Python's setup script will parse CPPFLAGS to find the include
directories, but it doesn't look at -isystem, only at -I. So it is actually
quite easy to fix.

 The reason that it got reverted so quickly without looking for a real fix is
that this was just before 2016.08-rc1, so the revert looked like the easy way
out. And nobody took the time back then to try to fix the issue fundamentally.

 For reference: the failures occur when building in a minimal environment
(particularly, no system zlib devel package). It happened for
host-python-setuptools, tvheadend and mongodb, at least.

 Regards,
 Arnout

-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Arnout Vandecappelle]

On 08/10/2018 12:51, Lothar Felten wrote:
> Patch dtc to accept libfdt include guards with and without leading underscore.
> A compiler warning is added to notify the user.
> 
> Signed-off-by: Lothar Felten <lothar.felten@gmail.com>

 At the Buildroot meeting, we agreed that the warning is OK, so I extended the
commit message and applied to master, thanks.

 Regards,
 Arnout

> ---
>  ...de-guards-for-older-kernel-u-boot-sources.patch | 42 ++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
>  create mode 100644 package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
> 
> diff --git a/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
> new file mode 100644
> index 0000000000..40cb0bdb2a
> --- /dev/null
> +++ b/package/dtc/0001-Fix-include-guards-for-older-kernel-u-boot-sources.patch
> @@ -0,0 +1,42 @@
> +From b1f8b84489c96465b63485b884238b61d31ca84d Mon Sep 17 00:00:00 2001
> +From: Lothar Felten <lothar.felten@gmail.com>
> +Date: Mon, 8 Oct 2018 13:29:44 +0200
> +Subject: [PATCH 1/1] Fix include guards for older kernel/u-boot sources
> +
> +Linux kernels before 4.17 and U-Boot versions before 2018.07 use libfdt include guards with leading underscores.
> +Those have been removed in dtc-1.4.7.
> +This patch handles both include guard types and allows the compilation of older Linux kernel and u-boot sources.
> +
> +Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
> +---
> + libfdt/libfdt.h     | 4 ++++
> + libfdt/libfdt_env.h | 4 ++++
> + 2 files changed, 8 insertions(+)
> +
> +diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> +index 830b77e..bef4566 100644
> +--- a/libfdt/libfdt.h
> ++++ b/libfdt/libfdt.h
> +@@ -1,3 +1,7 @@
> ++#ifdef _LIBFDT_H
> ++#warning "Please consider updating your kernel and/or u-boot version"
> ++#define LIBFDT_H
> ++#endif
> + #ifndef LIBFDT_H
> + #define LIBFDT_H
> + /*
> +diff --git a/libfdt/libfdt_env.h b/libfdt/libfdt_env.h
> +index eb20538..6a61e6a 100644
> +--- a/libfdt/libfdt_env.h
> ++++ b/libfdt/libfdt_env.h
> +@@ -1,3 +1,7 @@
> ++#ifdef _LIBFDT_ENV_H
> ++#warning "Please consider updating your kernel and/or u-boot version"
> ++#define LIBFDT_ENV_H
> ++#endif
> + #ifndef LIBFDT_ENV_H
> + #define LIBFDT_ENV_H
> + /*
> +-- 
> +2.11.0
> +
> 

[Buildroot] [PATCH 1/1] package/dtc: fix include guards for older kernel/u-boot

[Peter Korsgaard]

>>>>> "Lothar" == Lothar Felten <lothar.felten@gmail.com> writes:

 > Patch dtc to accept libfdt include guards with and without leading underscore.
 > A compiler warning is added to notify the user.

 > Signed-off-by: Lothar Felten <lothar.felten@gmail.com>

Committed to 2018.08.x, thanks.

-- 
Bye, Peter Korsgaard