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Date:      Sat, 27 Jun 2026 16:18:38 +0200
From:      Harry Schmalzbauer <freebsd@omnilan.de>
To:        ShengYi Hung <aokblast@FreeBSD.org>, src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org
Subject:   hwpstate_intel i386 build workaround [Was: Re: git: 7b26353a59d6 - main - hwpstate_intel: Disable package control on hybrid CPU]
Message-ID:  <21a39777-c38e-4805-abdc-b1c19183bce1@omnilan.de>
In-Reply-To: <6a1e7b3b.1a45a.91f6820@gitrepo.freebsd.org>
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On 2026-06-02 08:42, ShengYi Hung wrote:
> The branch main has been updated by aokblast:
>
> URL: https://cgit.FreeBSD.org/src/commit/?id=7b26353a59d66dc1bc611fd042a49b9e3bd13699
>
> commit 7b26353a59d66dc1bc611fd042a49b9e3bd13699
> Author:     ShengYi Hung <aokblast@FreeBSD.org>
> AuthorDate: 2026-06-01 09:46:37 +0000
> Commit:     ShengYi Hung <aokblast@FreeBSD.org>
> CommitDate: 2026-06-02 06:41:41 +0000
>
>      hwpstate_intel: Disable package control on hybrid CPU
>      
>      In package control mode, the performance of all cores depends on the
>      most recent value written to the request field. If the last write comes
>      from an E-core, all cores are forced to align with the E-core
>      performance level, resulting in significant performance degradation.
>      Therefore, package control is disabled on hybrid-core systems.
>      
>      Reviewed by:    olce
>      MFC after:      2 weeks
>      Sponsored by:   The FreeBSD Foundation
>      Sponsored by:   Framework Computer Inc
>      Differential Revision: https://reviews.freebsd.org/D57377
> ---
>   sys/x86/cpufreq/hwpstate_intel.c | 21 +++++++++++++++++++++


In lieu of a proper fix, due to lacking skills, I'm working around i386 
incompatibility with this diff:

diff --git a/sys/x86/cpufreq/hwpstate_intel.c 
b/sys/x86/cpufreq/hwpstate_intel.c
index db8600d7b89a..b9b68f1b14d0 100644
--- a/sys/x86/cpufreq/hwpstate_intel.c
+++ b/sys/x86/cpufreq/hwpstate_intel.c
@@ -321,6 +321,7 @@ sysctl_epp_select(SYSCTL_HANDLER_ARGS)
         return (ret);
  }

+#ifndef __i386__
  static void
  intel_hwpstate_hybrid_cb(void *ctx)
  {
@@ -328,11 +329,14 @@ intel_hwpstate_hybrid_cb(void *ctx)

         atomic_add_32(small_cores, PCPU_GET(small_core));
  }
+#endif

  void
  intel_hwpstate_identify(driver_t *driver, device_t parent)
  {
+#ifndef __i386__
         uint32_t small_cores = 0;
+#endif

         if (device_find_child(parent, "hwpstate_intel", 
DEVICE_UNIT_ANY) != NULL)
                 return;
@@ -353,6 +357,7 @@ intel_hwpstate_identify(driver_t *driver, device_t 
parent)
         if ((cpu_power_eax & CPUTPM1_HWP) == 0)
                 return;

+#ifndef __i386__
         /*
          * On hybrid-core systems, package-level control cannot be used.
          * It may cause all cores to run at the E-core frequency because
@@ -363,6 +368,7 @@ intel_hwpstate_identify(driver_t *driver, device_t 
parent)
             intel_hwpstate_hybrid_cb, smp_no_rendezvous_barrier, 
&small_cores);
         if (small_cores > 0 && small_cores < mp_ncores)
                 hwpstate_pkg_ctrl_enable = false;
+#endif

         if (BUS_ADD_CHILD(parent, 10, "hwpstate_intel", 
device_get_unit(parent))
             == NULL)

I know i386 is not supported anymore.
Just in case anybody else wants to keep i368-stable/15 for bhyve guests 
for example, where cpufreq(4) isn't attaching anyways.

Thanks,

-harry
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