* [dpdk-dev] [PATCH] eal/windows: add sys/queue.h.
@ 2021-08-05 17:33 William Tu
2021-08-10 21:05 ` Nick Connolly
0 siblings, 1 reply; 5+ messages in thread
From: William Tu @ 2021-08-05 17:33 UTC (permalink / raw)
To: dev; +Cc: dmitry.kozliuk, sergey.madaminov
When compiling OVS, lib/dpdk.c, found the missing header.
In file included from ../lib/dpdk.c:27:
C:\temp\dpdk\include\rte_log.h:24:10: fatal error: 'sys/queue.h' file
not found
^~~~~~~~~~~~~
1 warning and 1 error generated.
Signed-off-by: William Tu <u9012063@gmail.com>
---
lib/eal/windows/include/meson.build | 4 ++++
lib/eal/windows/include/sys/meson.build | 6 ++++++
2 files changed, 10 insertions(+)
create mode 100644 lib/eal/windows/include/sys/meson.build
diff --git a/lib/eal/windows/include/meson.build b/lib/eal/windows/include/meson.build
index b3534b025f..875cc1cf0d 100644
--- a/lib/eal/windows/include/meson.build
+++ b/lib/eal/windows/include/meson.build
@@ -8,3 +8,7 @@ headers += files(
'rte_virt2phys.h',
'rte_windows.h',
)
+
+sys_headers = []
+subdir('sys')
+install_headers(sys_headers, subdir: 'sys')
diff --git a/lib/eal/windows/include/sys/meson.build b/lib/eal/windows/include/sys/meson.build
new file mode 100644
index 0000000000..6896cbf678
--- /dev/null
+++ b/lib/eal/windows/include/sys/meson.build
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright 2021 VMware, Inc
+
+sys_headers += files(
+ 'queue.h',
+)
--
2.32.0.windows.2
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [dpdk-dev] [PATCH] eal/windows: add sys/queue.h.
2021-08-05 17:33 [dpdk-dev] [PATCH] eal/windows: add sys/queue.h William Tu
@ 2021-08-10 21:05 ` Nick Connolly
2021-08-10 22:33 ` Dmitry Kozlyuk
0 siblings, 1 reply; 5+ messages in thread
From: Nick Connolly @ 2021-08-10 21:05 UTC (permalink / raw)
To: William Tu, dev; +Cc: dmitry.kozliuk, sergey.madaminov
> diff --git a/lib/eal/windows/include/meson.build b/lib/eal/windows/include/meson.build
> index b3534b025f..875cc1cf0d 100644
> --- a/lib/eal/windows/include/meson.build
> +++ b/lib/eal/windows/include/meson.build
> @@ -8,3 +8,7 @@ headers += files(
> 'rte_virt2phys.h',
> 'rte_windows.h',
> )
> +
> +sys_headers = []
> +subdir('sys')
> +install_headers(sys_headers, subdir: 'sys')
> diff --git a/lib/eal/windows/include/sys/meson.build b/lib/eal/windows/include/sys/meson.build
> new file mode 100644
> index 0000000000..6896cbf678
> --- /dev/null
> +++ b/lib/eal/windows/include/sys/meson.build
> @@ -0,0 +1,6 @@
> +# SPDX-License-Identifier: BSD-3-Clause
> +# Copyright 2021 VMware, Inc
> +
> +sys_headers += files(
> + 'queue.h',
> +)
Hi William,
If I've understood this change correctly it will create a sys/queue.h
header in the build/include folder.
This seems like a reasonable approach to handle missing functionality,
but unfortunately it is problematic.
An application that links against DPDK is likely to be dealing with
similar issues with missing functionality
and providing a definition in the DPDK includes can conflict with the
approach taken by the application
(in this instance there could be two versions of sys/queue.h in the
include paths leading to ambiguity).
After discussion, the approach adopted by the DPDK community is that:
* DPDK should depend only on the C library and not require POSIX
functionality from the underlying
system (headers, definitions etc). Missing functionality should be
implemented within the DPDK
code.
* DPDK should not export POSIX functionality into the environment
(symbols, macros, headers etc)
to avoid these definitions clashing with the application.
In this instance, it seems that rte_log.h depends upon the system having
sys/queue.h which is not
a standard C dependency. The appropriate response here (based on the
above approach) is to remove
the sys/queue.h dependency from rte_log.h and ensure that it only
depends upon rte_* definitions
contained within the DPDK.
Regards,
Nick
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [dpdk-dev] [PATCH] eal/windows: add sys/queue.h.
2021-08-10 21:05 ` Nick Connolly
@ 2021-08-10 22:33 ` Dmitry Kozlyuk
2021-08-11 8:34 ` Nick Connolly
0 siblings, 1 reply; 5+ messages in thread
From: Dmitry Kozlyuk @ 2021-08-10 22:33 UTC (permalink / raw)
To: Nick Connolly; +Cc: William Tu, dev, sergey.madaminov
2021-08-10 22:05 (UTC+0100), Nick Connolly:
> > diff --git a/lib/eal/windows/include/meson.build b/lib/eal/windows/include/meson.build
> > index b3534b025f..875cc1cf0d 100644
> > --- a/lib/eal/windows/include/meson.build
> > +++ b/lib/eal/windows/include/meson.build
> > @@ -8,3 +8,7 @@ headers += files(
> > 'rte_virt2phys.h',
> > 'rte_windows.h',
> > )
> > +
> > +sys_headers = []
> > +subdir('sys')
> > +install_headers(sys_headers, subdir: 'sys')
> > diff --git a/lib/eal/windows/include/sys/meson.build b/lib/eal/windows/include/sys/meson.build
> > new file mode 100644
> > index 0000000000..6896cbf678
> > --- /dev/null
> > +++ b/lib/eal/windows/include/sys/meson.build
> > @@ -0,0 +1,6 @@
> > +# SPDX-License-Identifier: BSD-3-Clause
> > +# Copyright 2021 VMware, Inc
> > +
> > +sys_headers += files(
> > + 'queue.h',
> > +)
>
> Hi William,
>
> If I've understood this change correctly it will create a sys/queue.h
> header in the build/include folder.
> This seems like a reasonable approach to handle missing functionality,
> but unfortunately it is problematic.
>
> An application that links against DPDK is likely to be dealing with
> similar issues with missing functionality
> and providing a definition in the DPDK includes can conflict with the
> approach taken by the application
> (in this instance there could be two versions of sys/queue.h in the
> include paths leading to ambiguity).
>
> After discussion, the approach adopted by the DPDK community is that:
>
> * DPDK should depend only on the C library and not require POSIX
> functionality from the underlying
> system (headers, definitions etc). Missing functionality should be
> implemented within the DPDK
> code.
> * DPDK should not export POSIX functionality into the environment
> (symbols, macros, headers etc)
> to avoid these definitions clashing with the application.
>
> In this instance, it seems that rte_log.h depends upon the system having
> sys/queue.h which is not
> a standard C dependency. The appropriate response here (based on the
> above approach) is to remove
> the sys/queue.h dependency from rte_log.h and ensure that it only
> depends upon rte_* definitions
> contained within the DPDK.
Hi William and Nick,
rte_log.h doesn't need sys/queue.h include at all.
Unfortunately, other public headers need it.
Worse, they use TAILQ_ENTRY in structures and TAILQ_FOREACH in macros.
We discussed this offline with Tyler and he approved installing <sys/queue.h>,
but it is right that doing so would be against the policy.
What we can do:
1. Introduce `rte_queue.h` (name can be better) that is env-specific:
1.1. For Linux and FreeBSD it just includes <sys/queue.h>
and renames a few macros that are used in headers to RTE_xxx.
1.2. For Windows it defines the same RTE_xxx macros in a way
compatible with the <sys/queue.h> version used to build DPDK.
2. Add #include <sys/queue.h> in <rte_os_shim.h>:
Linux and FreeBSD will include a system header,
Windows will use the bundled one.
This way application are not exposed to non-RTE symbols,
at the same time RTE_xxx are binary-compatible with what DPDK
implementation expects (and outside of Windows there is no change in fact).
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [dpdk-dev] [PATCH] eal/windows: add sys/queue.h.
2021-08-10 22:33 ` Dmitry Kozlyuk
@ 2021-08-11 8:34 ` Nick Connolly
2021-08-11 15:18 ` William Tu
0 siblings, 1 reply; 5+ messages in thread
From: Nick Connolly @ 2021-08-11 8:34 UTC (permalink / raw)
To: Dmitry Kozlyuk; +Cc: William Tu, dev, sergey.madaminov
> What we can do:
>
> 1. Introduce `rte_queue.h` (name can be better) that is env-specific:
>
> 1.1. For Linux and FreeBSD it just includes <sys/queue.h>
> and renames a few macros that are used in headers to RTE_xxx.
> 1.2. For Windows it defines the same RTE_xxx macros in a way
> compatible with the <sys/queue.h> version used to build DPDK.
>
> 2. Add #include <sys/queue.h> in <rte_os_shim.h>:
> Linux and FreeBSD will include a system header,
> Windows will use the bundled one.
>
> This way application are not exposed to non-RTE symbols,
> at the same time RTE_xxx are binary-compatible with what DPDK
> implementation expects (and outside of Windows there is no change in fact).
+1
Nick
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [dpdk-dev] [PATCH] eal/windows: add sys/queue.h.
2021-08-11 8:34 ` Nick Connolly
@ 2021-08-11 15:18 ` William Tu
0 siblings, 0 replies; 5+ messages in thread
From: William Tu @ 2021-08-11 15:18 UTC (permalink / raw)
To: Nick Connolly; +Cc: Dmitry Kozlyuk, dpdk-dev, Sergey Madaminov
On Wed, Aug 11, 2021 at 1:34 AM Nick Connolly <nick.connolly@mayadata.io> wrote:
>
>
> > What we can do:
> >
> > 1. Introduce `rte_queue.h` (name can be better) that is env-specific:
> >
> > 1.1. For Linux and FreeBSD it just includes <sys/queue.h>
> > and renames a few macros that are used in headers to RTE_xxx.
> > 1.2. For Windows it defines the same RTE_xxx macros in a way
> > compatible with the <sys/queue.h> version used to build DPDK.
> >
> > 2. Add #include <sys/queue.h> in <rte_os_shim.h>:
> > Linux and FreeBSD will include a system header,
> > Windows will use the bundled one.
> >
> > This way application are not exposed to non-RTE symbols,
> > at the same time RTE_xxx are binary-compatible with what DPDK
> > implementation expects (and outside of Windows there is no change in fact).
>
> +1
> Nick
Hi Nick and Dmitry,
Thanks for such a detailed explanation!
I sent the v2 patch, hopefully I understand you guys correctly.
William
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-08-05 17:33 [dpdk-dev] [PATCH] eal/windows: add sys/queue.h William Tu
2021-08-10 21:05 ` Nick Connolly
2021-08-10 22:33 ` Dmitry Kozlyuk
2021-08-11 8:34 ` Nick Connolly
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