Re: [Xen-devel] Xen's Linux kernel config options V2

["Luis R. Rodriguez" <mcgrof@xxxxxxxxxxxxxxxx>]

On Fri, Feb 6, 2015 at 4:07 AM, Stefano Stabellini
<stefano.stabellini@xxxxxxxxxxxxx> wrote:
> On Thu, 5 Feb 2015, Luis R. Rodriguez wrote:
>> On Wed, Feb 4, 2015 at 6:57 AM, Stefano Stabellini
>> <stefano.stabellini@xxxxxxxxxxxxx> wrote:
>> > On Wed, 4 Feb 2015, David Vrabel wrote:
>> >> On 16/12/14 16:21, Juergen Gross wrote:
>> >> > Hi,
>> >> >
>> >> > This is a design proposal for a rework of the config options on the
>> >> > Linux kernel which are related to Xen.
>> >> >
>> >> > The need to do so arose from the fact that it is currently not
>> >> > possible to build the Xen frontend drivers for a non-pvops kernel,
>> >> > e.g. to run them in a HVM-domain. There are more drawbacks in the
>> >> > current config options to which I'll come later.
>> >> >
>> >> > Option                          Selects                 Depends
>> >> > ----------------------------------------------------------------------
>> >> > XEN
>> >> >   XEN_PV(x86)                   XEN_HAVE_PVMMU
>> >> >                                 PARAVIRT
>> >> >                                 PARAVIRT_CLOCK
>> >> >   XEN_PVH(x86)                  XEN_PVHVM
>> >> >                                 PARAVIRT
>> >> >                                 PARAVIRT_CLOCK
>> >> >   XEN_PVHVM                     PARAVIRT
>> >> >                                 PARAVIRT_CLOCK
>> >
>> > PARAVIRT_CLOCK and PARAVIRT are x86 specific.
>> > Given that there is no CONFIG_PV or CONFIG_PVH or even CONFIG_PVHVM on
>> > arm and arm64 as there is just one type of guest, I would rather just
>> > have CONFIG_XEN there.
>>
>> Interesting, right now we have as part of the recommended change for
>> XEN_BACKEND:
>>
>> Option                          Selects                 Depends
>> ----------------------------------------------------------------------
>> XEN
>>   XEN_BACKEND                   SWIOTLB_XEN(arm,arm64)  XEN_PV(x86) ||
>>                                                         XEN_PVH(x86) ||
>>                                                         XEN_PVHVM
>>
>> How would we ensure to enable XEN_BACKEND for arm then?
>
> I thought that you wanted to turn XEN_BACKEND into a user selectable
> option.  On arm and arm64 this option wouldn't depend on anything
> (except CONFIG_XEN).

OK sure, that maps to this dependency list then:

ARM || ARM64 || ( X86 && (XEN_PV || XEN_PVH || XEN_PVHVM )

>> >> >   XEN_BACKEND                   SWIOTLB_XEN(arm,arm64)  XEN_PV(x86) ||
>> >> >                                                         XEN_PVH(x86) ||
>> >> >                                                         XEN_PVHVM
>> >> >     XEN_BLKDEV_BACKEND
>> >> >     XEN_PCIDEV_BACKEND(x86)
>> >> >     XEN_SCSI_BACKEND
>> >> >     XEN_NETDEV_BACKEND
>> >> >   PCI_XEN(x86)                  SWIOTLB_XEN
>> >> >   XEN_DOM0                      XEN_BACKEND             XEN_PV(x86) ||
>> >> >                                 PCI_XEN(x86)            XEN_PVH(x86)
>> >> >     XEN_ACPI_HOTPLUG_MEMORY                             XEN_STUB
>> >> >     XEN_ACPI_HOTPLUG_CPU                                XEN_STUB
>> >> >     XEN_MCE_LOG(x86)
>> >> >   XEN_MAX_DOMAIN_MEMORY(x86)
>> >> >   XEN_SAVE_RESTORE(x86)
>> >> >   XEN_DEBUG_FS
>> >> >   XEN_WDT
>> >> >   XEN_BALLOON
>> >> >     XEN_SELFBALLOONING                                  XEN_TMEM
>> >> >     XEN_BALLOON_MEMORY_HOTPLUG
>> >> >     XEN_SCRUB_PAGES
>> >> >   XENFS                         XEN_PRIVCMD
>> >> >     XEN_COMPAT_XENFS
>> >> >   XEN_SYS_HYPERVISOR
>> >> >   XEN_DEV_EVTCHN
>> >> >   XEN_GNTDEV
>> >> >   XEN_GRANT_DEV_ALLOC
>> >> >   SWIOTLB_XEN
>> >> >   XEN_TMEM
>> >
>> > not available on arm and arm64
>>
>> Can you clarify if you meant only XEN_TMEM or all the above here?
>
> Only TMEM, sorry for being terse

That was listed as one of the example Kconfig entries which are
currently not available on other architectures despite not being
architecture specific, the other one being XEN_DEBUG_FS. So to be
clear -- do we not want XEN_TMEM for arm in the future ?

>> >> >   XEN_PRIVCMD
>> >> >   XEN_STUB(x86_64)                                      BROKEN
>> >> >   XEN_ACPI_PROCESSOR(x86)
>> >> >   XEN_HAVE_PVMMU
>> >
>> > x86 specific
>>
>> Likewise, all of the above quoted options ?
>
> only XEN_HAVE_PVMMU

Updated.

>> >> >   XEN_EFI(x64)
>> >
>> > FYI soon to be available on arm
>>
>> OK thanks.
>>
>> >> >   XEN_XENBUS_FRONTEND
>> >> > XEN_FRONTEND                    XEN
>> >> >                                 XEN_XENBUS_FRONTEND
>> >> >   XEN_FBDEV_FRONTEND            INPUT_XEN_KBDDEV_FRONTEND
>> >> >   XEN_BLKDEV_FRONTEND
>> >> >   HVC_XEN_FRONTEND              HVC_XEN
>> >> >   TCG_XEN
>> >> >   XEN_PCIDEV_FRONTEND           PCI_XEN
>> >
>> > x86 specific for the moment
>>
>> All?
>
> XEN_PCIDEV_FRONTEND and PCI_XEN

Updated.

>> >> >   XEN_SCSI_FRONTEND
>> >> >   INPUT_XEN_KBDDEV_FRONTEND
>> >> >   XEN_NETDEV_FRONTEND
>> >> >   XEN_PLATFORM_PCI
>> >
>> > definitely x86 only
>>
>> All?
>
> only XEN_PLATFORM_PCI

Updated.

 Luis

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