Re: [PATCH] doc: update parameters to use for mlx5 on Windows

[Andre Muezerie <andremue@linux.microsoft.com>]

On Tue, Jul 15, 2025 at 02:03:45PM +0200, Dariusz Sosnowski wrote:
> Hi,
> 
> On Mon, May 05, 2025 at 08:22:41AM -0700, Andre Muezerie wrote:
> > The linker parameters to use with MSVC and Clang differ.
> > Showing explicitly what to use with each in the documentation.
> > 
> > Signed-off-by: Andre Muezerie <andremue@linux.microsoft.com>
> > ---
> >  doc/guides/platform/mlx5.rst | 20 ++++++++++++++++----
> >  1 file changed, 16 insertions(+), 4 deletions(-)
> > 
> > diff --git a/doc/guides/platform/mlx5.rst b/doc/guides/platform/mlx5.rst
> > index ab3107209a..7a5bea3b49 100644
> > --- a/doc/guides/platform/mlx5.rst
> > +++ b/doc/guides/platform/mlx5.rst
> > @@ -268,14 +268,26 @@ configured by the ``ibverbs_link`` build option:
> >  Compilation on Windows
> >  ~~~~~~~~~~~~~~~~~~~~~~
> >  
> > -The DevX SDK location must be set through CFLAGS/LDFLAGS,
> > -either::
> > +The DevX SDK location must be set through CFLAGS/LDFLAGS.
> > +When compiling with MSVC, use either::
> >  
> > -   meson.exe setup "-Dc_args=-I\"%DEVX_INC_PATH%\"" "-Dc_link_args=-L\"%DEVX_LIB_PATH%\"" ...
> > +   meson.exe setup "-Dc_args=-I\"%DEVX_INC_PATH%\""
> > +   "-Dc_link_args=-LIBPATH:\"%DEVX_LIB_PATH%\"" -Denable_stdatomic=true ...
> 
> This long command line can be split for readability,
> using caret as line break:
> 
> 	meson.exe setup ^
> 	  "-Dc_args=-I\"%DEVX_INC_PATH%\"" ^
> 	  "-Dc_link_args=-LIBPATH:\"%DEVX_LIB_PATH%\"" ^
> 	  -Denable_stdatomic=true ^
> 	  ...
> 
> The same applies to commands for clang.
> 
> >  
> >  or::
> >  
> > -   set CFLAGS=-I"%DEVX_INC_PATH%" && set LDFLAGS=-L"%DEVX_LIB_PATH%" && meson.exe setup ...
> > +   set CFLAGS=-I"%DEVX_INC_PATH%" && set LDFLAGS=-LIBPATH:"%DEVX_LIB_PATH%" &&
> > +   meson.exe setup -Denable_stdatomic=true ...
> 
> && are not really needed here and
> it can be splitted into multiple lines for readability:
> 
> 	set CFLAGS=-I"%DEVX_INC_PATH%"
> 	set LDFLAGS=-LIBPATH:"%DEVX_LIB_PATH%"
> 	meson.exe setup -Denable_stdatomic=true ...
> 
> The same applies to commands for clang.
> 
> > +
> > +When compiling with Clang, use either::
> > +
> > +   meson.exe setup "-Dc_args=-I\"%DEVX_INC_PATH%\""
> > +   "-Dc_link_args=-Wl,-LIBPATH:\"%DEVX_LIB_PATH%\"" ...
> 

Thanks, that indeed makes the commands easier to read.

> Shouldn't clang linker parameters stay as it was previously i.e., "-L..."?

Not on Windows. It can be confirmed by looking at build\meson-logs\meson-log.txt,
where it can be seen that the -L option ends up being ignored:

Sanity check compiler command line: clang sanitycheckc.c -o sanitycheckc.exe -IV:\soft\MLNX_WinOF2_DevX_SDK\inc -D_FILE_OFFSET_BITS=64 -Wl,-LV:\soft\MLNX_WinOF2_DevX_SDK\lib
Sanity check compile stdout:
LINK : warning LNK4044: unrecognized option '/LV:\soft\MLNX_WinOF2_DevX_SDK\lib'; ignored

As a result the lib mlx5devx is not found:

Has header "mlx5devx.h" : YES
Library mlx5devx found: NO

I'll send out a new version of this patch with the changes suggested.

Best regards,
Andre Muezerie

> 
> > +
> > +or::
> > +
> > +   set CFLAGS=-I"%DEVX_INC_PATH%" && set LDFLAGS=-Wl,-LIBPATH:"%DEVX_LIB_PATH%" &&
> > +   meson.exe setup ...
> >  
> >  
> >  .. _mlx5_common_env:
> 
> Best regards,
> Dariusz Sosnowski