Re: [PATCH v4 04/19] bsd-user: Clean up includes

[Michael S. Tsirkin]

On Fri, Jan 27, 2023 at 02:54:30PM +0000, Peter Maydell wrote:
> On Thu, 19 Jan 2023 at 14:42, Warner Losh <imp@bsdimp.com> wrote:
> >
> > Also, why didn't you move sys/resource.h and other such files
> > to os-dep.h? I'm struggling to understand the rules around what
> > is or isn't included where?
> 
> The rough rule of thumb is that if some OS needs a compatibility
> fixup or workaround for a system header (eg not every mmap.h
> defines MAP_ANONYMOUS; on Windows unistd.h has to come before
> time.h) then we put that header include and the compat workaround
> into osdep.h. This avoids "only fails on obscure platform" issues
> where somebody puts a header include into some specific .c file
> but not the compat workaround, and it works on the Linux host
> that most people develop and test on and we only find the
> problem later.
> 
> There's also no doubt some includes there for historical
> reasons, and some which really are "everybody needs these"
> convenience ones. But we should probably not add new
> includes to osdep.h unless they fall into the "working around
> system header issues" bucket.
> 
> thanks
> -- PMM


BTW maybe we should teach checkpatch about that rule:
if a header is in osdep do not include it directly.

-- 
MST