On Fri, Mar 20, 2020 at 3:19 PM Thomas Gleixner tglx@linutronix.de wrote:

The x86 CPU matching based on struct x86_cpu_id:

• is using an inconsistent macro mess with pointlessly duplicated and slightly different local macros. Finding the places is an art as there is no consistent name space at all.

• is still mostly based on C89 struct initializers which rely on the ordering of the struct members. That's proliferated forever as every new driver just copies the mess from some exising one.

A recent offlist conversation about adding more match criteria to the CPU matching logic instead of creating yet another set of horrors, reminded me of a pile of scripts and patches which I hacked on a few years ago when I tried to add something to struct x86_cpu_id.

That stuff was finally not needed and ended up in my ever growing todo list and collected dust and cobwebs, but (un)surprisingly enough most of it still worked out of the box. The copy & paste machinery still works as it did years ago.

There are a few places which needed extra care due to new creative macros, new check combinations etc. and surprisingly ONE open coded proper C99 initializer.

It was reasonably simple to make it at least compile and pass a quick binary equivalence check.

The result is a X86_MATCH prefix based set of macros which are reflecting the needs of the usage sites and shorten the base macro which takes all possible parameters (vendor, family, model, feature, data) and uses proper C99 initializers.

So extensions of the match logic are trivial after that.

Thank you, Thomas!

Briefly looking to the code, I like the idea. I'll do (minor) comments on individual patches.

I see it incorporates my previous attempts to extend this, but now it looks better.

The patch set is against Linus tree and has trivial conflicts against linux-next.

The diffstat is: 71 files changed, 525 insertions(+), 472 deletions(-)

but the extra lines are pretty much kernel-doc documentation which I added to each of the new macros. The usage sites diffstat is:

70 files changed, 393 insertions(+), 471 deletions(-)

Thoughts?

Thanks,

    tglx