[dpdk-dev] MinGW guide

[dpdk-dev] MinGW guide

[Thomas Monjalon]

The Windows user guide is referencing a general link to download MinGW:
	http://mingw-w64.org/doku.php/download
For those who want to install MinGW on Windows, I thing it is simpler
to give this more direct link:
	http://mingw-w64.org/doku.php/download/mingw-builds
It avoids hesitating between different bundles (Cygwin, Msys2, Win-Builds, etc).

Then when installing mingw-w64-install.exe, a choice must be done
between threads POSIX or Win32.
If I understand well, POSIX must be chosen?
If it is important, it should be documented in my opinion.

Re: [dpdk-dev] MinGW guide

[Dmitry Kozlyuk]

On Sat, 13 Jun 2020 10:55:14 +0200
Thomas Monjalon <thomas@monjalon.net> wrote:

> The Windows user guide is referencing a general link to download MinGW:
> 	http://mingw-w64.org/doku.php/download
> For those who want to install MinGW on Windows, I thing it is simpler
> to give this more direct link:
> 	http://mingw-w64.org/doku.php/download/mingw-builds
> It avoids hesitating between different bundles (Cygwin, Msys2, Win-Builds, etc).

Agreed, at least while no package manager is used. 
I believe the most direct link would be this one:
	https://sourceforge.net/projects/mingw-w64/files/

> Then when installing mingw-w64-install.exe, a choice must be done
> between threads POSIX or Win32.
> If I understand well, POSIX must be chosen?

Yes. DPDK config/meson.build now links with pthread if linker is not link.exe.

Note that maybe this can be relaxed (test needed!), i. e. link with pthread
if it is found, otherwise use shim. Benefit, if this works: no runtime
dependency on "libwinpthread-1.dll" for Windows.

-- 
Dmitry Kozlyuk

Re: [dpdk-dev] MinGW guide

[Tal Shnaiderman]

> Subject: Re: MinGW guide
> 
> On Sat, 13 Jun 2020 10:55:14 +0200
> Thomas Monjalon <thomas@monjalon.net> wrote:

[snip]

> > Then when installing mingw-w64-install.exe, a choice must be done
> > between threads POSIX or Win32.
> > If I understand well, POSIX must be chosen?
> 
> Yes. DPDK config/meson.build now links with pthread if linker is not link.exe.
> 

Where do we actually use pthread in Windows? 

> Note that maybe this can be relaxed (test needed!), i. e. link with pthread if
> it is found, otherwise use shim. Benefit, if this works: no runtime
> dependency on "libwinpthread-1.dll" for Windows.

I was sure, since we create the threads with Win32 API (CreateThread), the correct option is Win32.
My mingw-w64 is installed with that option and I didn't see issues with it.

> 
> --
> Dmitry Kozlyuk

Re: [dpdk-dev] MinGW guide

[Dmitry Kozlyuk]

On Mon, 15 Jun 2020 09:25:07 +0000
Tal Shnaiderman <talshn@mellanox.com> wrote:

> > Subject: Re: MinGW guide
> > 
> > On Sat, 13 Jun 2020 10:55:14 +0200
> > Thomas Monjalon <thomas@monjalon.net> wrote:  
> 
> [snip]
> 
> > > Then when installing mingw-w64-install.exe, a choice must be done
> > > between threads POSIX or Win32.
> > > If I understand well, POSIX must be chosen?  
> > 
> > Yes. DPDK config/meson.build now links with pthread if linker is not link.exe.
> >   
> 
> Where do we actually use pthread in Windows?

Nowhere indeed. Probably it was my mistake to link with it when adding MinGW
support. Shim is always used anyway.

> 
> > Note that maybe this can be relaxed (test needed!), i. e. link with pthread if
> > it is found, otherwise use shim. Benefit, if this works: no runtime
> > dependency on "libwinpthread-1.dll" for Windows.  
> 
> I was sure, since we create the threads with Win32 API (CreateThread), the correct option is Win32.
> My mingw-w64 is installed with that option and I didn't see issues with it.

Then I'm totally wrong. Your way MinGW-w64 produces an executable without
dependencies (apart from system libraries), so this should be preferred. I
tried and it works for me.

-- 
Dmitry Kozlyuk