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x86 idle: deprecate "no-hlt" cmdline param

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We'd rather that modern machines not check if HLT works on
every entry into idle, for the benefit of machines that had
marginal electricals 15-years ago.  If those machines are still running
the upstream kernel, they can use "idle=poll".  The only difference
will be that they'll now invoke HLT in machine_hlt().

cc: x86@kernel.org # .39.x
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Len Brown 2011-04-01 15:41:17 -04:00
parent 99c6322143
commit cdaab4a0d3
2 changed files with 12 additions and 0 deletions
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11
Documentation/feature-removal-schedule.txt
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@ -24,6 +24,17 @@ Who: Len Brown <len.brown@intel.com>
----------------------------
What: x86_32 "no-hlt" cmdline param
When: 2012
Why: remove a branch from idle path, simplify code used by everybody.
This option disabled the use of HLT in idle and machine_halt()
for hardware that was flakey 15-years ago. Today we have
"idle=poll" that removed HLT from idle, and so if such a machine
is still running the upstream kernel, "idle=poll" is likely sufficient.
Who: Len Brown <len.brown@intel.com>
----------------------------
What: PRISM54
When: 2.6.34

1
arch/x86/kernel/cpu/bugs.c
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@ -19,6 +19,7 @@
static int __init no_halt(char *s)
{
WARN_ONCE(1, "\"no-hlt\" is deprecated, please use \"idle=poll\"\n");
boot_cpu_data.hlt_works_ok = 0;
return 1;
}