port-i386/38634: x86 kernels no longer produces information about cpus

[chris%NetBSD.org@localhost]

>Number:         38634
>Category:       port-i386
>Synopsis:       x86 kernels no longer produces information about cpus
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-i386-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon May 12 11:20:01 +0000 2008
>Originator:     Chris Gilbert
>Release:        -current as of Sun May 11 21:50:06 UTC 2008
>Organization:
>Environment:
>Description:
dmesg used to contain information about cache sizes and feature flags for cpus 
(even if it was wrong for non-cpu0s).

This information has been completely stripped and appears to have moved to 
userland.

This will cause issues should cpuctl and the kernel have different code.  As a 
bug in the kernel code may not be present in cpuctl and a cache or tlb maybe 
detected incorrectly.

To confirm the CPU caches and other information now requires you can get to 
userland, which may not be possible on all systems (eg a test boot on a new 
processor, or other installation issues)

It also doesn't allow verification of changes to the kernel's detection of the 
CPU features without adding the printf's back in.

See PR 37461 for why the code was removed (even though the submitter asked for 
it to be made verbose/debug, rather than stripped)
>How-To-Repeat:
boot a -current kernel, while wishing to check if cache and tlbs are correctly 
detected, and find nothing is actually displayed.
>Fix:
Add and aprint_verbose proper detection of CPU features on x86.

The code could be placed into a common library for both kernel and userland to 
use the same code.