On Wed, Sep 16 2026, David Matlack wrote: > On Tue, Sep 15, 2026 at 8:31 PM Zhu Yanjun <[email protected]> wrote: >> 在 2026/7/28 15:09, David Matlack 写道: > >> > CONFIG_64BIT is now required to enable CONFIG_PCI_LIVEUPDATE so that the >> > domain and bdf can be guaranteed to fit in an unsigned long and be used >> > as the xarray key. > >> > diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig >> > index 3781e2b5f095..8af20f558086 100644 >> > --- a/drivers/pci/Kconfig >> > +++ b/drivers/pci/Kconfig >> > @@ -273,7 +273,7 @@ config VGA_ARB_MAX_GPUS >> > >> > config PCI_LIVEUPDATE >> > bool "PCI Live Update Support" >> > - depends on PCI && LIVEUPDATE >> > + depends on PCI && LIVEUPDATE && 64BIT >> >> One question about adding 64BIT to the dependency: >> >> As I understand it, enabling CONFIG_64BIT essentially means that we are >> building a 64-bit kernel, and a 32-bit architecture cannot normally >> enable CONFIG_64BIT. >> >> If that is the case, would depends on 64BIT be necessary here? Or is PCI >> Live Update already inherently restricted to 64-bit architectures by the >> existing LIVEUPDATE/architecture configuration, so that this dependency >> would be redundant? >> >> If this problem has already discussed, I am very sorry about this. > > The necessity is that the PCI core needs to store more than 32-bits in > the unsigned long xarray key (see the snippet above). The dependency > on CONFIG_64BIT ensures that unsigned long is big enough. We could > probably remove the dependency but I would rather wait until someone > with a 32-bit build has a real use-case for using PCI_LIVEUPDATE > before putting any effort into it.
KHO or live update themselves don't support 32-bit platforms and there are no plans to do so either. So I don't think you even need to have a dependency on 64BIT in PCI_LIVEUPDATE. Only 64 bit architectures define ARCH_SUPPORTS_KEXEC_HANDOVER, so PCI_LIVEUPDATE and others indirectly inherit the dependency. If you'd like to be extra safe, then probably you should add a dependency to 64BIT in KEXEC_HANDOVER directly. Though I think that can be a separate patch independent from this series. -- Regards, Pratyush Yadav
