Re: Invalid link generation for equations

[Mauro Carvalho Chehab <mchehab+huawei@kernel.org>]

On Wed, 25 Mar 2026 15:11:57 -0600
Jonathan Corbet <corbet@lwn.net> wrote:

> Shuah Khan <skhan@linuxfoundation.org> writes:
> 
> >> OK, so this is more than passing strange...I can't reproduce that
> >> problem locally.  The HTML I get is:
> >> 
> >>    <img src="../_images/math/d9936822[...]
> >> 
> >> On docs.kernel.org, instead:
> >> 
> >>    <img src="_images/math/d9936822[...]
> >> 
> >> Note the missing "../".
> >> 
> >> I will confess that I don't have a great understanding of how imgmath
> >> works and how that link gets set.  We could "fix" the problem generally
> >> by setting imgmath_embed=True, but it would be good to understand what's
> >> actually happening here.  
> >
> > Respect SPHINX_IMGMATH (for html docs only) in Documentation/conf.py
> > might explain why imgmath_embed=True works?
> >
> > # Load math renderer:
> > # For html builder, load imgmath only when its dependencies are met.
> > # mathjax is the default math renderer since Sphinx 1.8.
> > have_latex = have_command("latex")
> > have_dvipng = have_command("dvipng")
> > load_imgmath = have_latex and have_dvipng
> >
> > Without setting imgmath_embed=true, math_renderer is mathjax which is
> > default since Sphinx 1.8  
> 
> We default to imgmath if the requisite utilities (latex, dvipng) are
> installed on the system; perhaps that's not ideal, but it's what we have
> done for a while.  It all seems to be working as expected, except that
> the <img> element has the wrong URI in it.  Strange.

Looking at this changelog from Akira:

	6b0d3e7c5888 ("docs/conf.py: Treat mathjax as fallback math renderer")

It mentions that this is kept due to epub output. On a quick search:

	https://github.com/sphinx-doc/sphinx/issues/1570

I'm not sure how this is handled in PDF, but mathjax seems to be
specific for html output only.
	
Thanks,
Mauro