Xen Linux Kernel Delta

The Xen Linux kernel upstream delta

Linux distributions are using xen with the Linux kernel but the Linux kernel is typically patched with support for features and enhancements which are not yet upstream. This page documents the delta with the Linux kernel and provides a detailed analysis / status update on each of the patches for each Linux distribution. The purpose of this is page is for Linux distributions to describe each patch being carried forward for their delta, analyze whether or not it can be upstreamed and if so how, see who can or will work on it, and also identify patches which can or should be dropped. The delta for Linux distributions is very similar but SUSE likely caries the largest delta, our end objective should be to distill which delta is common and identify who is working on what. There's quite a bit of patches which likely are no longer needed due to a proper replacement already being upstream or because they are no longer applicable, identifying this also needs to be done.

Xen OpenSUSE 13.1 delta

OpenSUSE's 13.1 kernel sources can be found at on the [[1]] repository on the origin/openSUSE-13.1 branch. The xen specific changes are under the kernel-source/patches.xen/ directory. Below is an analysis of each patch, and its status.

Patches already upstream - ignore

 * xen-sys-suspend
 * xen-clockevents
 * xen-netback-generalize
 * xen-netback-multiple-tasklets
 * xen-netback-kernel-threads
 * xen-blk*-indirect*
 * xen-x86-per-cpu-vcpu-info
 * xen-x86-bzImage

Patches require verification if upstream replacement exists

 * pci-guestdev
 * xen-mem-hotplug
 * xen-privcmd-hcall-preemption - a replacement was at least posted; its not clear if and when it went upstream
 * xen-*multi-page-ring - does not provide core functionality, not critical but folks should respin for upstream if not done so yet

Patches some folks are working on upstreaming

 * xen-x86-EFI:

Someone is working on this?

 * ipv6-no-autoconf:

Luis R. Rodriguez is working a replacement for this, the work consists of a proper way to address adding the root bridge block feature, and also fixing bridging code to address this early without userspace, patches are ongoing review upstream

Features provided by some patches which need upstream effort

 * 500GB+ RAM support - xen-x86_64-note-init-p2m, xen-x86_64-unmapped-initrd, maybe others
 * pvSCSI - partly in xen3-auto-xen-drivers.diff with some fixes in xen3-patch-*
 * pvUSB - partly in xen3-auto-xen-drivers.diff with some fixes in xen3-patch-*
 * user mode pvclock - xen-x86_64-vread-pvclock
 * expose min/max limits of domain ballooning - xen-balloon-max-target

 * retaining tasklet support in netback - xen-netback-kernel-threads:

some folks use this to get better throughput at the expense of worse interactivity. This differs from the upstream approach in retaining tasklets as an option

 * add support for new operation type BLKIF_OP_PACKET - xen-blkif-op-packet
 * implement forwarding of CD-ROM specific commands - xen-blkfront-cdrom
 * CDROM removable media-present attribute plus handling code - xen-blkback-cdrom
 * in HVM guests do not take over the CDROM device - xen-blkfront-hvm-no-cdrom
 * force proper address translation in DCDBAS - xen-dcdbas
 * netback: use multicall for sending multiple notifications - xen-netback-notify-multi
 * pass trigger mode and polarity information to Xen for all interrupts - xen-setup-gsi

Debian testing delta

TBD