Re: [PATCH v2] ethdev: add Linux ethtool link mode conversion

[Stephen Hemminger <stephen@networkplumber.org>]

On Thu, 29 Feb 2024 17:58:13 +0100
Morten Brørup <mb@smartsharesystems.com> wrote:

> > From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> > Sent: Thursday, 29 February 2024 17.45
> > 
> > On Thu, 29 Feb 2024 16:42:56 +0100
> > Thomas Monjalon <thomas@monjalon.net> wrote:
> >   
> > > +/* Link modes sorted with index as defined in ethtool.
> > > + * Values are speed in Mbps with LSB indicating duplex.
> > > + *
> > > + * The ethtool bits definition should not change as it is a kernel  
> > API.  
> > > + * Using raw numbers directly avoids checking API availability
> > > + * and allows to compile with new bits included even on an old  
> > kernel.  
> > > + *
> > > + * The array below is built from bit definitions with this shell  
> > command:  
> > > + *   sed -rn 's;.*(ETHTOOL_LINK_MODE_)([0-9]+)([0-9a-zA-Z_]*).*=  
> > *([0-9]*).*;'\  
> > > + *           '[\4] = \2, /\* \1\2\3 *\/;p'  
> > /usr/include/linux/ethtool.h |  
> > > + *   awk '/_Half_/{$3=$3+1","}1'
> > > + */
> > > +static uint32_t link_modes[] = {  
> > 
> > Make it const please.
> > 
> > You could add meson rule to generate it and then use non-numeric tags.  
> 
> However you do it, make sure it cross builds. The kernel/ethtool on the target system may differ from the one on the build system.
> 

If the build system is older, the speed table will be smaller. And the code should just print "Unknown"
If the build system is newer, then the table will be larger than kernel ever returns which is Ok.