Subject: Re: [PATCH] Documentation/powerpc: Remove retired CPUs from list of supported CPUs

From: Michael Ellerman <[email-masked]>
Date: Wed, 10 Jul 2024 20:50:41 +1000

Christophe Leroy <[email-masked]> writes:
> 601, power4, 401, 403, 405, e200 and IBM-A2 support was removed by
> by following commits:
> - Commit 8b14e1dff067 ("powerpc: Remove support for PowerPC 601")
> - Commit 471d7ff8b51b ("powerpc/64s: Remove POWER4 support")
> - Commit 1b5c0967ab8a ("powerpc/40x: Remove support for IBM 403GCX")
> - Commit 39c8bf2b3cc1 ("powerpc: Retire e200 core (mpc555x processor)")
> - Commit fb5a515704d7 ("powerpc: Remove platforms/wsp and associated
> pieces")

There was also: 468a33028edd ("powerpc: Drop support for pre-POWER4 cpus")

> Remove them from the list of supported CPUs.

The CPU families doc is not intended to be a list of supported CPUs,
it's more of a family tree which includes the currently supported CPUs.

Even when I first added it there were CPUs mentioned that weren't
supported. (I realise the paragraph at the top of the file doesn't make
that clear)

I don't mind removing cores that are unsupported and unconnected to
other things, eg. A2, e200 and the 40x.

But for 601 and the early POWER cores I'd rather we marked the
unsupported ones with an asterisk or something. That way the family tree
still connects and includes all the history, otherwise I think it risks
being confusing.

Or maybe we use a different box outline (~) for unsupported cores? eg:

   +~~~~~~~~~~~~~~+                 +~~~~~~~~~~~~~~~~+
   |  Old POWER   | --------------> | RS64 (threads) |
   +~~~~~~~~~~~~~~+                 +~~~~~~~~~~~~~~~~+
          |
          |
          v
   +~~~~~~~~~~~~~~+                 +----------------+      +------+
   |     601      | --------------> |      603       | ---> | e300 |
   +~~~~~~~~~~~~~~+                 +----------------+      +------+
          |                                 |
          |                                 |
          v                                 v
   +--------------+    +-----+      +----------------+      +-------+
   |     604      |    | 755 | <--- |    750 (G3)    | ---> | 750CX |
   +--------------+    +-----+      +----------------+      +-------+
          |                                 |                   |
          |                                 |                   |
          v                                 v                   v
   +~~~~~~~~~~~~~~+                 +----------------+      +-------+
   | 620 (64 bit) |                 |      7400      |      | 750CL |
   +~~~~~~~~~~~~~~+                 +----------------+      +-------+
          |                                 |                   |
          |                                 |                   |
          v                                 v                   v
   +~~~~~~~~~~~~~~+                 +----------------+      +-------+
   |  POWER3/630  |                 |      7410      |      | 750FX |
   +~~~~~~~~~~~~~~+                 +----------------+      +-------+

cheers