Not-ready features and speedups =============================== Legend: PRI1: We're totally lame if this doesn't get in PRI2: Would be nice PRI3: Not very important drivers/block/ ~~~~~~~~~~~~~~ o Framework for selecting IO schedulers. This is the main one really. Once this is in place we can drop in new schedulers any old time, no risk. PRI1 o Anticipatory scheduler. Working OK now, still has problems with seeky OLTP-style loads. PRI1 o CFQ scheduler. Seems to work but Jens planning significant rework. PRI2 o cryptoloop: jmorris: There's no cryptoloop in the 2.4 mainline kernel, but I think every distro ships some version. It would probably be useful to have crypto natively supported in 2.6, with backward compatibility for the majority of 2.4 users. problem: lack of a loop maintainer PRI2 o viro: paride drivers need a big cleanup PRI2 drivers/char/rtc/ ~~~~~~~~~~~~~~~~~ o rmk, trini: add support for alarms to the existing generic rtc driver. PRI2 device mapper ~~~~~~~~~~~~~ o ioctl interface cleanup patch is ready (redo the structure layouts) PRI1 o A port of the 2.4 snapshot target is in progress PRI1 o the fs interface to dm needs to be redone. gregkh was going to work on this. viro is interested in seeing work thus-far. PRI2 drivers/net/wireless/ ~~~~~~~~~~~~~~~~~~~~~ (Jean Tourrilhes ) o get latest orinoco changes from David. PRI1 o get the latest airo.c fixes from CVS. This will hopefully fix problems people have reported on the LKML. PRI1 o get HostAP driver in the kernel. No consolidation of the 802.11 management across driver can happen until this one is in (which is probably 2.7.X material). I think Jouni is mostly ready but didn't find time for it. PRI2 o get more wireless drivers into the kernel. The most "integrable" drivers at this point seem the NWN driver, Pavel's Spectrum driver and the Atmel driver. PRI1 o The last two drivers mentioned above are held up by firmware issues (see flamewar on LKML a few days ago). So maybe fixing those firmware issues should be a requirement for 2.6.X, because we can expect more wireless devices to need firmware upload at startup coming to market. (in progress?) PRI1 drivers/usb/gadget/ ~~~~~~~~~~~~~~~~~~~ o rmk: SA11xx USB client/gadget code (David B has been doing some work on this, and keeps trying to prod me, but unfortunately I haven't had the time to look at his work, sorry David.) PRI3 fs/ ~~~ o ext3 lock_kernel() removal: that part works OK and is mergeable. But we'll also need to make lock_journal() a spinlock, and that's deep surgery. Patches exist in -mm. PRI1 o ext3 and ext2 block allocators have serious failure modes - interleaved allocations. PRI3 o 32bit quota needs a lot more testing but may work now PRI2 o Integrate Chris Mason's 2.4 reiserfs ordered data and data journaling patches. They make reiserfs a lot safer. Ordered: PRI2 data journalled: PRI3 o (Trond:) Yes: I'm still working on an atomic "open()", i.e. one where we short-circuit the usual VFS path_walk() + lookup() + permission() + create() + .... bullsh*t... I have several reasons for wanting to do this (all of them related to NFS of course, but much of the reasoning applies to *all* networked file systems). 1) The above sequence is simply not atomic on *any* networked filesystem. 2) It introduces a sh*tload of completely unnecessary RPC calls (why do a 'permission' RPC call when the server is in *any* case going to tell you whether or not this operations is allowed. Why do a 'lookup()' when the 'create()' call can be made to tell you whether or not a file already exists). 3) It is incompatible with some operations: the current create() doesn't pass an 'EXCLUSIVE' flag down to the filesystems. 4) (NFS specific?) open() has very different cache consistency requirements when compared to most other VFS operations. I'd very much like for something like Peter Braam's 'lookup with intent' or (better yet) for a proper dentry->open() to be integrated with path_walk()/open_namei(). I'm still working on the latter (Peter has already completed the lookup with intent stuff). PRI2 (?) o (Chuck Lever ): NFS O_DIRECT support must be completed. The best approach is to fall back to something like the 2.4 NFS O_DIRECT support, which issues RPCs synchronously and uses the RPC completion mechanism to wait for I/O completion. PRI2 o rmk: update acorn partition parsing code - making all acorn schemes appear in check.c so we don't have to duplicate the scanning of multiple types, and adding support for eesox partitions. PRI2 o atomic i_size patches PRI1 o viro: cleaning up options-parsers in filesystems. (patch exists, needs porting). PRI2 o aio: fs IO isn't async at present. suparna has restart patches, they're in -mm. Need to get Ben to review/comment. PRI1. kernel/ ~~~~~~~ o rusty: Zippel's Reference count simplification. Tricky code, but cuts about 120 lines from module.c. Patch exists, needs stressing. PRI3 o rusty: /proc/kallsyms. What most people really wanted from /proc/ksyms. Patch exists. PRI3 o rusty: Fix module-failed-init races by starting module "disabled". Patch exists, requires some subsystems (ie. add_partition) to explicitly say "make module live now". Without patch we are no worse off than 2.4 etc. PRI1 o Integrate userspace irq balancing daemon. PRI2 o kexec. Seems to work, was in -mm. PRI3 o rmk: modules / /proc/kcore / vmalloc This needs sorting and testing to ensure that stuff like gdb vmlinux /proc/kcore works as expected. I believe this is the only show stopper preventing any ARM platform being built in Linus' kernel. Patch exists in -mm, nobody has tested it for the above afaik. PRI1 o kcore is a problem for ia64 (Tony Luck) Patch exists in -mm. PRI1 o rmk: lib/inflate.c must not use static variables (causes these to be referenced via GOTOFF relocations in PIC decompressor. We have a PIC decompressor to avoid having to hard code a per platform zImage link address into the makefiles.) PRI2 o klibc merge? PRI2 mm/ ~~~ o objrmap: concerns over page reclaim performance at high sharing levels, and interoperation with nonlinear mappings is hairy. o Reintroduce and make /proc/sys/vm/freepages writable again so that boxes can be tuned for heavy interrupt load. Patch exists in -mm. PRI1 o oxymoron's async write-error-handling patch PRI1 o dropbehind for large files PRI2 net/ ~~~~ (davem) o Real serious use of IPSEC is hampered by lack of MPLS support. MPLS is a switching technology that works by switching based upon fixed length labels prepended to packets. Many people use this and IPSEC to implement VPNs over public networks, it is also used for things like traffic engineering. A good reference site is: http://www.mplsrc.com/ Anyways, an existing (crappy) implementation exists. I've almost completed a rewrite, I should have something in the tree next week. PRI1 o Sometimes we generate IP fragments when it truly isn't necessary. The way IP fragmentation is specified, each fragment must be modulo 8 bytes in length. So suppose the device has an MTU that is not 0 modulo 8, ethernet even classifies in this way. 1500 == (8 * 187) + 4 Our IP fragmenting engine can fragment on packets that are sized within the last modulo 8 bytes of the MTU. This happens in obscure cases, but it does happen. I've proposed a fix to Alexey, whereby very late in the output path we check the packet, if we fragmented but the data length would fit into the MTU we unfragment the packet. This is low priority, because technically it creates suboptimal behavior rather than mis-operation. PRI1 net/*/netfilter/ ~~~~~~~~~~~~~~~~ o Lots of misc. cleanups, which are happening slowly. PRI2 o davem: Netfilter needs to stop linearizing packets as much as possible. Zerocopy output packets are basically undone by netfilter becuase all of it assumed it was working with linear socket buffers. Rusty is fixing this piece by piece. He is nearly done with this work. PRI1 power management ~~~~~~~~~~~~~~~~ (Pat) There is some preliminary work at bk://ldm.bkbits.net/linux-2.5-power, though I'm currently in the process of reworking it. It includes: o New device power management core code, both for individual devices, and for global state transitions. PRI1 o A generic user interface for triggering system power state transitions. PRI1 o Arch-independent code for performing state transitions, that calls platform-specific methods along the way. PRI1 o A better suspend-to-disk mechanism than swsusp. There are various other details to be worked out, which are the real fun part. And of course, driver support, but that is something that can happen at any time. (Alan) PRI2 o Frame buffer restore codepaths (that requires some deep PCI magic) PRI2 o XFree86 hooks PRI2 o AGP restoration PRI2 o DRI restoration (davej/Alan: not super-critical, can crash laptop on restore. davej looking into it.) PRI2 o IDE suspend/resume without races (Ben is looking at this a little) PRI2 o Pat: There are already CPU device structures; MTRRs should be a dynamically registered interface of CPUs, which implies there needs to be some other glue to know that there are MTRRs that need to be saved/restored. PRI1 global ~~~~~~ o 64-bit dev_t. Seems almost ready, but it's not really known how much work is still to do. Patches exist in -mm but with the recent rise of the neo-viro I'm not sure where things are at. PRI1 o We need a kernel side API for reporting error events to userspace (could be async to 2.6 itself) (Prototype core based on netlink exists) PRI2 o Kai: Introduce a sane, easy and standard way to build external modules PRI2 o Kai: Allow separate src/objdir PRI2 o general confusion over firmware policy: o do we mandate that it be uploaded from userspace? o Is binary-blob-in-kernel-image OK? o Each driver (wireless, scsi, etc) seems to do it in a different, private manner. gregkh: patch exists, drivers can be ported to use new infrastructure at any time. PRI1 o larger cpumask_t - supporting more than BITS_PER_LONG CPUs. wli: patch exists. ia32, ppc are done. ppc64 in progress. Needs work for other architectures. PRI1 o pavel: ioctl32 emulation should be shared across architectures. (patch exists). PRI2 drivers ~~~~~~~ o Alan: Cardbus/PCMCIA requires all Russell's stuff is merged to do multiheader right and so on PRI1 drivers/acpi/ ~~~~~~~~~~~~~ o alan: VIA APIC stuff is one bit of this, there are also some other reports that were caused by ACPI not setting level v edge trigger some times PRI1 o mochel: it seems the acpi irq routing code could use a serious rewrite. grover: The problem is the ACPI irq routing code is trying to piggyback on the existing MPS-specific data structures, and it's generally a hack. So yes mochel is right, but it is also purging MPS-ities from common code as well. I've done some preliminary work in this area and it doesn't seem to break anything (yet) but a rewrite in this area imho should not be rushed out the door. And, I think the above bugs can be fixed w/o the rewrite. PRI2 o mochel: ACPI suspend doesn't work. Important, not cricital. Pat is working it. PRI2 drivers/block/ ~~~~~~~~~~~~~~ o Floppy is almost unusably buggy still akpm: we need more people to test & report. alan: "Floppy has worked for me since the patches that went in 2.5.69-ac and I think -bk somewhere" PRI1 drivers/char/ ~~~~~~~~~~~~~ o Alan: Multiple serious bugs in the DRI drivers (most now with patches thankfully). "The badness I know about is almost entirely IRQ mishandling. DRI failing to mask PCI irqs on exit paths." (This is understood and fixed in DRI CVS) PRI1 o Various suspect things in AGP. PRI1 drivers/ide/ ~~~~~~~~~~~~ (Alan) o IDE requires bio walking "Bartlomiej has IDE multisector working" (does that mean it's fixed?) PRI1 o IDE PIO has occasional unexplained PIO disk eating reports PRI1 o IDE has multiple zillions of races/hangs in 2.5 still PRI1 o IDE scsi needs rewriting PRI2 o IDE needs significant reworking to handle Simplex right PRI2 o IDE hotplug handling for 2.5 is completely broken still PRI2 o There are lots of other IDE bugs that wont go away until the taskfile stuff is included, the locking bugs that allow any user to hang the IDE layer in 2.5, and some other updates are forward ported. (esp. HPT372N). PRI1 drivers/isdn/ ~~~~~~~~~~~~~ (Kai, rmk) o isdn_tty locking is completely broken (cli() and friends) PRI2 o fix lots of remaining bugs in the isdn link layer / hisax protocol layer / hisax subdrivers, so that at least 99% of the users have a usable ISDN subsystem PRI1 o fix other drivers PRI2 o lots more cleanups, adaption to recent APIs etc PRI3 o fixup tty-based ISDN drivers which provide TIOCM* ioctls (see my recent 3-set patch for serial stuff) Alternatively, we could re-introduce the fallback to driver ioctl parsing for these if not enough drivers get updated. PRI3 drivers/net/ ~~~~~~~~~~~~ o davej: Either Wireless network drivers or PCMCIA broke somewhen. A configuration that worked fine under 2.4 doesn't receive any packets. Need to look into this more to make sure I don't have any misconfiguration that just 'happened to work' under 2.4 PRI1 drivers/scsi/ ~~~~~~~~~~~~~ o qlogic follies: - jejb: Merge the feral driver. It covers all qlogic chips: 1020 all the way up to 23xxx. mjacob is promising a "major" rewrite which eliminates this as a candidate for immediate inclusion. Panics on my parisc hardware, works on my ia64. BK tree is http://linux-scsi.bkbits.net/scsi-isp-2.5 - qla2xxx: only for FC chips. Has significant build issues. hch promises to send me a "must fix" list for this. I plan not to merge this until I at least see how Qlogic responds to the issues. Can't currently build this for my only fibre card (a qla2100). BK tree is at http://linux-scsi.bkbits.net/scsi-qla2xxx-2.5 - I think the best plan currently is not to merge either of these, but keep shadow BK trees for them (thus holding out the possibility of merger) to see how they evolve. I agree with hch that feral seems to be in the better shape but, barring directions to the contrary, I can't see why both shouldn't be included eventually. PRI2 arch/i386/ ~~~~~~~~~~ o Also PC9800 merge needs finishing to the point we want for 2.6 (not all). PRI3 o ES7000 wants merging (now we are all happy with it). That shouldn't be a big problem. PRI2 o davej: PAT support (for mtrr exhaustion w/ AGP) PRI2 o 2.5.x won't boot on some 440GX alan: Problem understood now, feasible fix in 2.4/2.4-ac. (440GX has two IRQ routers, we use the $PIR table with the PIIX, but the 440GX doesnt use the PIIX for its IRQ routing). Fall back to BIOS for 440GX works and Intel concurs. PRI1 o 2.5.x doesn't handle VIA APIC right yet. 1. We must write the PCI_INTERRUPT_LINE 2. We have quirk handlers that seem to trash it. PRI1 o ACPI needs the relax patches merging to work on lots of laptops alan: ACPI relax stuff is in 2.4-ac, compaq workaround is in next -ac coming. These seem to deliver the goods - toshibas now work a treat. Some other relax bits are being discussed (assume local0 starts 0 etc) and progress looks great. This can occur before 2.6 or during. PRI1 o ECC driver questions are not yet sorted (DaveJ is working on this) (Dan Hollis) alan: ECC - I have some test bits from Dan's stuff - they need no kernel core changes for most platforms. That means we can treat it as a random driver merge. PRI3 o alan: 2.4 has some fixes for tsc handling bugs. One where some bioses in SMM mode mess up our toggle on the time high/low or mangle the counter and one where a few chips need religious use of _p for timer access and we don't do that. This is forward porting little bits of fixup. ACPI HZ stuff we can't trap - a lot of ACPI is implemented as outb's triggering SMM traps PRI1 arch/x86_64/ ~~~~~~~~~~~~ (Andi) o time handling is broken. Need to move up 2.4 time.c code. PRI1 o Another report of a crash at shutdown on Simics with no iommu when all memory was used. Could be related to the one above. PRI1 o NMI watchdog seems to tick too fast PRI2 o not very well tested. probably more bugs lurking. PRI1 o need to coredump 64bit vsyscall code with dwarf2 PRI2 o move 64bit signal trampolines into vsyscall code and add dwarf2 for it. PRI1 o describe kernel assembly with dwarf2 annotations for kgdb (currently waiting on some binutils changes for this) PRI3 arch/alpha/ ~~~~~~~~~~~ o rth: Ptrace writes are broken. This means we can't (reliably) set breakpoints or modify variables from gdb. PRI1 arch/arm/ ~~~~~~~~~ o rmk: missing raw keyboard translation tables for all ARM machines. Haven't even looked into this at all. This could be messy since there isn't an ARM architecture standard. I'm presently hoping that it won't be an issue. If it does, I guess we'll see drivers/char/keyboard.c explode. PRI2 arch/others/ ~~~~~~~~~~~~ o SH/SH-64 need resyncing, as do some other ports. No impact on mainstream platforms hopefully. PRI2 o IA64 needs merging, has impact on core code PRI1 arch/s390/ ~~~~~~~~~ o A nastly memory management problem causes random crashes. These appear to be fixed/hidden by the objrmap patch, more investigation is needed. PRI1 drivers/s390/ ~~~~~~~~~~~~~ o Early userspace and 64 bit dev_t will allow the removal of most of dasd_devmap.c and dasd_genhd.c. PRI2 o The 3270 console driver needs to be replaced with a working one (prototype is there, needs to be finished). PRI2 o Minor interface changes are pending in cio/ when the z990 machines are out. There are some more things being worked on that are either post-2.6.0 or are likely to remain outside of the official kernel (i.e. not for your list): PRI3 o Jan Glauber is working on a fix for the timer issues related to running on virtualized CPUs (wall-clock vs. cpu time). PRI1 o new zfcp fibre channel driver PRI3 o the qeth driver will become GPL soon PRI3 o a block device driver for ramdisks shared among virtual machines PRI3 o driver for crypto hardware PRI2 o 'claw' network device driver PRI3