Messages in this thread | | | Date | Tue, 13 Sep 2022 17:50:36 -0500 | From | Bjorn Helgaas <> | Subject | Re: [PATCH v2 08/10] x86/Kconfig: make CONFIG_PCI_CNB20LE_QUIRK depend on X86_32 |
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On Sun, Sep 11, 2022 at 10:47:09AM +0200, Mateusz Jończyk wrote: > I was unable to find a good description of the ServerWorks CNB20LE > chipset. However, it was probably exclusively used with the Pentium III > processor (this CPU model was used in all references to it that I > found where the CPU model was provided: dmesgs in [1] and [2]; > [3] page 2; [4]-[7]). > > As is widely known, the Pentium III processor did not support the 64-bit > mode, support for which was introduced by Intel a couple of years later. > So it is safe to assume that no systems with the CNB20LE chipset have > amd64 and the CONFIG_PCI_CNB20LE_QUIRK may now depend on X86_32. > > Additionally, I have determined that most computers with the CNB20LE > chipset did have ACPI support and this driver was inactive on them. > I have submitted a patch to remove this driver, but it was met with > resistance [8].
Only because removing the driver appeared to have no demonstrated benefit and risked breaking old machines.
Making this depend on X86_32 seems plausible to me.
> [8] Bjorn Helgaas, "Re: [PATCH] x86/pci: drop ServerWorks / Broadcom > CNB20LE PCI host bridge driver" > https://lore.kernel.org/lkml/20220318165535.GA840063@bhelgaas/T/ > > Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Borislav Petkov <bp@alien8.de> > Cc: Dave Hansen <dave.hansen@linux.intel.com> > Cc: x86@kernel.org > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: Ira W. Snyder <ira.snyder@gmail.com> > Cc: Bjorn Helgaas <helgaas@kernel.org> > --- > v2: make CONFIG_PCI_CNB20LE_QUIRK depend on X86_32 > (previously only help text and description were changed) > upgrade short description. > > arch/x86/Kconfig | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index fdfe8b7e895a..31f778b0cd0b 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -2739,13 +2739,21 @@ config MMCONF_FAM10H > depends on X86_64 && PCI_MMCONFIG && ACPI > > config PCI_CNB20LE_QUIRK > - bool "Read CNB20LE Host Bridge Windows" if EXPERT > - depends on PCI > + bool "Read PCI host bridge windows from the CNB20LE chipset" if EXPERT > + depends on X86_32 && PCI > help > Read the PCI windows out of the CNB20LE host bridge. This allows > PCI hotplug to work on systems with the CNB20LE chipset which do > not have ACPI. > > + The ServerWorks (later Broadcom) CNB20LE was a chipset designed > + most probably only for Pentium III. > + > + To find out if you have such a chipset, search for a PCI device with > + 1166:0009 PCI IDs, for example by executing > + lspci -nn | grep '1166:0009' > + The code is inactive if there is none. > + > There's no public spec for this chipset, and this functionality > is known to be incomplete. > > -- > 2.25.1 >
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