Re: Xen's Linux kernel config options v3

[Juergen Gross <jgross@suse.com>]

On 02/07/2015 12:44 AM, Luis R. Rodriguez wrote:
> This is a third respin for a design proposal for a rework on the config options
> on the Linux kernel related to Xen. The frist two proposals came from Juergen,
> I'm taking on the work now as some other work I am doing is related to this.
> This third iteration addresses the feedback given on Juergen's last v2
> proposal. Let me know if there are any questions or any further feedback before
> we start addressing the changes.
>
> Reasons to consider a cleanup / reorganizing of the kconfig options:
>
> - Everything depends on Xen but that's obviously not right. For instance
>    we want to be able to build Xen frontend drivers for HVM domains without
>    the need for choosing a pvops kernel: currently the frontend drivers need
>    Xen configured which depends on PARAVIRT.
> - XEN should not depend on PAE, we can have HVM guests without PAE.
> - Some features are available for x86 only, in spite of these not being
>    architecture specific, e.g. XEN_DEBUG_FS
> - Be able to build a Dom0 using XEN_PVH(x86) without having to configure
>    XEN_HAVE_PVMMU(x86).
>
> Current Xen related config options are as follows:
>
> Legend:
>
> - The first column are the Xen config options. Indentation in this
>    column reflects the dependency between those options (e.g.
>    XEN_SCSI_BACKEND depends on XEN_BACKEND, which in turn depends on
>    XEN_DOM0, which depends on XEN).
> - The second column shows the options which are selected automatically
>    if the corresponding option in the first column is configured.
> - The last column shows additional dependencies which can't be shown via
>    the indentation level of the first column.
> - Some options or dependencies are architecture specific, they are
>    listed with the architecture requirements in parens (e.g. XEN_TMEM(x86)
>    which is available for x86 only).
> - Non-Xen options are mentioned only if they seem to be really relevant,
>    like e.g. PARAVIRT or BROKEN.
> - All listed options are user selectable, options which are not user selectable but
>    automatic are prefixed with a '*' on the left hand side to make emphasis
>
> Option                          Selects                 Depends
> ---------------------------------------------------------------------
> XEN                             PARAVIRT_CLOCK(x86)     PARAVIRT(x86)
>                                  XEN_HAVE_PVMMU(x86)
>                                  SWIOTLB_XEN(arm,arm64)
>    PCI_XEN(x86)                  SWIOTLB_XEN
>    XEN_DOM0                                              PCI_XEN(x86)
>      XEN_BACKEND
>        XEN_BLKDEV_BACKEND
>        XEN_PCIDEV_BACKEND(x86)
>        XEN_SCSI_BACKEND
>        XEN_NETDEV_BACKEND
>      XEN_ACPI_HOTPLUG_MEMORY                             XEN_STUB
>      XEN_ACPI_HOTPLUG_CPU                                XEN_STUB
>      XEN_MCE_LOG(x86)
>    XEN_ACPI_PROCESSOR(x86)				ACPI_PROCESSOR
> 							CPU_FREQ
>    XEN_PVHVM(x86)
>      XEN_PVH(x86)
>    XEN_MAX_DOMAIN_MEMORY(x86)
>    XEN_SAVE_RESTORE(x86)
>    XEN_DEBUG_FS(x86)
>    XEN_FBDEV_FRONTEND            XEN_XENBUS_FRONTEND
>                                  INPUT_XEN_KBDDEV_FRONTEND
>    XEN_BLKDEV_FRONTEND           XEN_XENBUS_FRONTEND
>    HVC_XEN
>      HVC_XEN_FRONTEND            XEN_XENBUS_FRONTEND
>    TCG_XEN                       XEN_XENBUS_FRONTEND
>    XEN_PCIDEV_FRONTEND           PCI_XEN
>                                  XEN_XENBUS_FRONTEND
>    XEN_SCSI_FRONTEND             XEN_XENBUS_FRONTEND
>    INPUT_XEN_KBDDEV_FRONTEND     XEN_XENBUS_FRONTEND
>    XEN_WDT
>    XEN_BALLOON
>      XEN_SELFBALLOONING                                  XEN_TMEM
>      XEN_BALLOON_MEMORY_HOTPLUG
>      XEN_SCRUB_PAGES
>    XEN_DEV_EVTCHN
>    XENFS                         XEN_PRIVCMD
>      XEN_COMPAT_XENFS
>    XEN_SYS_HYPERVISOR
>    XEN_XENBUS_FRONTEND
>    XEN_GNTDEV
>    XEN_GRANT_DEV_ALLOC
>    SWIOTLB_XEN
>    XEN_TMEM(x86)
>    XEN_PRIVCMD
>    XEN_STUB(x86_64)                                      BROKEN
>    XEN_ACPI_PROCESSOR(x86)
>    XEN_HAVE_PVMMU
>    XEN_EFI(x64)
>    XEN_NETDEV_FRONTEND           XEN_XENBUS_FRONTEND
>
> After some feedback for the first draft I'd suggest the following:
>
> Option                          Selects                 Depends
> ----------------------------------------------------------------------
> XEN
>    XEN_PV(x86)                   XEN_HAVE_PVMMU(x86)
>                                  PARAVIRT
>                                  PARAVIRT_CLOCK
>    XEN_PVH(x86)                  XEN_PVHVM
>                                  PARAVIRT
>                                  PARAVIRT_CLOCK
>    XEN_PVHVM(x86)                PARAVIRT
>                                  PARAVIRT_CLOCK
>    XEN_BACKEND                   SWIOTLB_XEN(arm,arm64)  XEN_PV(x86) ||
>                                                          XEN_PVH(x86) ||
>                                                          XEN_PVHVM(x86)
> 				XEN_TMEM(x86)
> 				XEN_PRIVCMD

Wrong indentation of above 2 entries

Juergen

>      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_ACPI_PROCESSOR(x86)				ACPI_PROCESSOR
> 							CPU_FREQ
>      XEN_SAVE_RESTORE(x86)
>      XEN_DEBUG_FS
>      XEN_WDT
>    XEN_MAX_DOMAIN_MEMORY(x86)				XEN_HAVE_PVMMU(x86)
>    XEN_BALLOON
>      XEN_SELFBALLOONING                                  XEN_TMEM(x86)
>      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_STUB(x86_64)                                      BROKEN
>    XEN_ACPI_PROCESSOR(x86)
>   *XEN_HAVE_PVMMU(x86)					XEN_PV(x86)
>    XEN_EFI(x64)
>    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(x86)      PCI_XEN(x86)
>    XEN_SCSI_FRONTEND
>    INPUT_XEN_KBDDEV_FRONTEND
>    XEN_NETDEV_FRONTEND
>    XEN_PLATFORM_PCI(x86)
>
> Changes since v2:
>
>   * Add XEN_ACPI_PROCESSOR (Konrad)
>   * XEN_MAX_DOMAIN_MEMORY(x86) depends on XEN_HAVE_PVMMU(x86) now (Juergen).
>     Juergen will later replace this once he adds > 500 GiB pv-domains
>   * Clarifications on some lose options, we seem to want to keep these
>     user selectable to be able to allow userspace options which do not depend
>     on xen backend / frontends: ballooning, xenfs, sysfs, event dev, gntdev (Jan)
>   * Tons of clarifications on x86 specific options (Stefano), this includes
>     XEN_PVHVM(x86)
>
>    Luis
>
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