Linux Kernel 2.6.20 Released 240
diegocgteleline.es writes "After two months of development, Linux 2.6.20 has been released. This release includes two different virtualization implementations: KVM: full-virtualization capabilities using Intel/AMD virtualization extensions and a paravirtualization implementation usable by different hypervisors. Additionally, 2.6.20 includes PS3 support, a fault injection debugging feature, UDP-lite support, better per-process IO accounting, relative atime, relocatable x86 kernel, some x86 microoptimizations, lockless radix-tree readside, shared pagetables for hugetbl, and many other things. Read the list of changes for more details."
Re:Too many tlas? (Score:2, Informative)
Since I love the PHP and PERL implementations of associate arrays, I guess it's neat to have these data structures implemented directly in the kernel! Sounds like they might be using them as a sort of in-memory data store.
SixD
Re:Pretty amusing superbowl announcement (Score:2, Informative)
Re:Amazing (Score:5, Informative)
The latest ubuntu pre-release has the 2.6.20rc kernel. This will be 2.6.20 final (+patches) in the final "Feisty Fawn" release in a couple of months.
Also, I believe (but I'm not 100% sure) that fedora 7 will ship 2.6.20. Current pre-release (test1) and rawhide have 2.6.19.
Re:Too many tlas? (Score:5, Informative)
Lockless means it's doing something without locking everyone else from the data. Sometimes this means optimistic resolution (everyone try, and if it looks like it screwed up, try again!), sometimes it means keeping local read copies, sometimes it means something new and/or crazy. Lockless approaches are used when you have data that lots of threads must share but efficiency concerns or non-blocking requirements force you away from simply using a lock and blocking when someone else is playing with the data.
A radix-tree [wikipedia.org], as opposed to "radix-free", is a data structure used in certain applications, with operations dependent on the length of the key rather than the amount of data stored. In 2.6.20 [kernel.org] (and others), it's used to organize some information about the page cache.
This code is associated with the RCU, which you may recall is part of an SCO lawsuit. If you're interested in any other feature or changes, the kernel newbies site is instrumental!
Re:So... (Score:2, Informative)
Re:Relocatable on x86? (Score:5, Informative)
Re:Relocatable on x86? (Score:5, Informative)
Relocatable kernel support for x86
This feature (enabled with CONFIG_RELOCATABLE) isn't very noticeable for end-users but it's quite interesting from a kernel POV. Until now, it was a requeriment that a i386 kernel was loaded at a fixed memory address in order to work, loading it in a different place wouldn't work. This feature allows to compile a kernel that can be loaded at different 4K-aligned addresses, but always below 1 GB, with no runtime overhead. Kdump users (a feature introduced in 2.6.13 that it triggers kexec in a kernel crash in order to boot a kernel that has been previously loaded at a 'empty' address, then runs that kernel, saves the memory where the crashed kernel was placed, dumps it in a file and continues booting the system) will benefit from this because until now the "rescue kernel" need to be compiled with different configuration options in order to make it bootable at a different address. With a relocatable kernel, the same kernel can be boot at different addresses.
Re:Relocatable on x86? (Score:5, Informative)
Kernel Newbie's Detailed 2.6.20 list. (Score:5, Informative)
Short overview (for news sites, etc)
2.6.20 makes linux join to the virtualization trends. This release adds two virtualization implementations: A full-virtualization implementation that uses Intel/AMD hardware virtualization capabilities called KVM (http://kvm.sourceforge.net) and a paravirtualization implementation (http://lwn.net/Articles/194543) that can be used by different hypervisors (Rusty's lguest; Xen and Vmware in the future, etc),. But this release also adds initial Sony Playstation 3 support, a fault injection debugging feature (http://lwn.net/Articles/209257), UDP-lite support, better per-process IO accounting, relative atime, support for using swap files for suspend users, relocatable x86 kernel support for kdump users, small microoptimizations in x86 (sleazy FPU, regparm, support for the Processor Data Area, optimizations for the Core 2 platform), a generic HID layer, DEEPNAP power savings for PPC970, lockless radix-tree readside, shared pagetables for hugetbl, ARM support for the AT91 and iop13xx processors, full NAT for nf_conntrack and many other things.
Important things (AKA: ''the cool stuff'')
Sony Playstation 3 support
You may like the Wii or the 360 more, but only the PS3 is gaining official Linux support, written by Sony engineers. Notice that the support at this time is incomplete (apparently enabling it will not boot on a stock PS3) and it doesn't support the devices included like the graphics card, etc. (commit 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
Virtualization support through KVM
KVM (project page) adds a driver for Intel's and AMD's hardware virtualization extensions to the x86 architecture (KVM will not work in CPUs without virtualization capabilities). See the Virtualization wiki for more information about virtualization in Linux
The driver adds a character device (/dev/kvm) that exposes the virtualization capabilities to userspace. Using this driver, a process can run a virtual machine (a "guest") in a fully virtualized PC containing its own virtual hard disks, network adapters, and display. Each virtual machine is a process on the host; a virtual cpu is a thread in that process. kill(1), nice(1), top(1) work as expected. In effect, the driver adds a third execution mode to the existing two: we now have kernel mode, user mode, and guest mode. Guest mode has its own address space mapping guest physical memory (which is accessible to user mode by mmap()ing
32 and 64 bits guests are supported (but not x86-64 guests on x86-32 hosts!). For i386 guests and hosts, both pae and non-pae paging modes are supported. SMP hosts and UP guests are supported, SMP guests aren't (support will be added in the future). You also can start multiple virtual machines in a host. Performance currently is non-stellar, it will be improved by a lot with the future inclusion of KVM paravirtualization KVM support.
The Windows install currently bluescreens due to a problem with the virtual APIC, a fix is being worked on and will be added in future releases. A temporary workaround is to use an existing image or install through qemu - Windows 64-bit does not work either (commit)
Paravirtualization support for i386
Paravirtualization is the act of running a guest operating system, under control of a host system, where the guest has been ported to a virtual architecture which is almost like the hardware it is actually running on. This technique allows full guest systems to be run in a relatively efficient manner (continue reading this LWN article for more information). This allows to link different hypervisors (lguest/lhype/rustyvisor implements a hypervisor in 6.000 lines; Xen and Vmware will be probably ported to th
Re:OSX vs Vista vs Linux (Score:5, Informative)
Re:That's nice... (Score:2, Informative)
PS3 support (Score:3, Informative)
Re:OSX vs Vista vs Linux (Score:3, Informative)
Actually, that's a replacement for the Jell-o Tree, which had to be locked all the time to keep those darned kids out of it.
Come on, mod me Informative. I dare you.... 8^)
Re:kvm versus vmware (Score:5, Informative)
VMWare workstation actually does more than VMWare server, which is why it is not free. You can look up the comparison table on the VMWare site, but Workstation is usually more attractive to developers because it has (amongst other things):
My understanding is KVM provides the infrastructure for userland programs (such as VMWare, Xen) etc to access hardware virtualization services provided by late model Intel and AMD processors. Asking if KVM is a reasonable alternative to VMWare Server is not really a good way to frame the question - one day VMWare may use KVM for virtualisation. A better questions may be "which user-space virtualisation tool provides the best features for me as a user/developer/admin - Xen, VMWare, WidgetWorks" etc.
Re:Big FLASH (Score:3, Informative)
Re:Amazing (Score:3, Informative)
PS3 support not complete (Score:3, Informative)
Things may have changed but I'm stucking with my hand-patched 2.6.17 with zd1211 support for usb wifi.
I use the PS3 Linux quite a bit as a family-room computer. Sound is limited to 2-channel, but good quality. Video has no acceleration, but is still fast and looks good on our 720p TV. Unfortunately, the built-in WIFI doesn't work with Linux, and the Sony-provided kernel seems to lack any support for USB WIFI.
Re:Zombie process (Score:3, Informative)
Zombie Processes are not a bad thing. They're not memory leaks.
If you have a lot of zombie processes hanging around it's because of a bug in a program. It's pretty unlikely that it's a kernel bug.
Re:Pretty amusing superbowl announcement (Score:2, Informative)