Re: Drivers -- below the OS? [LWN.net]

Re: Drivers -- below the OS?

Posted Aug 9, 2007 15:24 UTC (Thu) by heckler (guest, #46684)
Parent article: Re: Drivers -- below the OS?

Mr. Linus T. implies that virtualization is just another attempt to reinvent the wheel, focusing his analogy on the shape of the wheel. It turns out; his analogy is right on target as it helps to dramatize that the OS folks are running on empty when it comes to appreciating the reality of virtualization. It's not the shape of the wheel that virtualization is changing. Rather, virtualization is fundamentally changing the architecture of the tire while adding clear and present business value to the owner of the car. Where once our wheels were white walls with an inner tube and often they lost air, went flat and thus we carried around a full size spare in the trunk. We now have tubeless tires that resist punctures, self heal, alert the driver to low tire pressure, can be filled with Nitrogen to improve MPG and the full size spare has been condensed into a tiny little backup we seldom need to use. And when was the last time you needed to replace your everyday tires with special "snow tires" when the going got tough? While the wheel is still indeed round, today's tires, provide better reliability, are agile enough to handle changing conditions, improve energy usage, run longer and you need less full size items. So it's true the wheel remains round. However, what virtualization is changing, underneath the OS stack, is dramatic. Our tires will still be round, but with the value of virtualization, they sure run better, stay inflated longer, need to be replaced less often and decrease the amount of power I consume while keeping my business moving forward. Virtualization - the shape remains the same, while the value increase, or as others have more eloquently stated "Virtualization is the most non-disruptive, disruptive technology". Let's not lose site of the car while we're kicking the tires :-)

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Re: Drivers -- below the OS?

Posted Aug 10, 2007 11:45 UTC (Fri) by landley (guest, #6789) [Link]

> while adding clear and present business value

Then you go on to mention "adding value" twice more, and then quote The
Innovator's Dilemma. It's a good book, which is why I reviewed it for
The Motley Fool in 1999:
http://www.fool.com/portfolios/rulemaker/1999/rulemaker99...

However, my question to you is, what's with all the pointy hair? Linus
is talking technology, and you're talking about marketing to corporate
customers. How are you _not_ making his point for him?

Adding layers neither reduces complexity nor adds stability. It never
has. It didn't with microkernels, it still doesn't now, and on a
conceptual level it's unlikely to start. One runaway driver does a DMA
to the wrong physical memory or lets a device lock the PCI bus and never
release it, and it's game over. Virtualization allows IBM to come up
with yet more glossy brochures to push mainframes as a replacement for
clusters of PCs (although the price of electricity and air conditioning
in rackmounted space has been making that case for them for years). But
for the millions of laptops out there, there's never enough RAM and
chopping it in half to share between two OS images is not an improvement.
(Of course I extensively use QEMU's ability to emulate Arm and Mips and
such, but I'm weird. :)

P.S. A few months ago I briefly had a HPaq laptop that was "built for
vista" and nothing else had drivers. (Ubuntu, Knoppix, nothing.) When I
returned it truthfully saying "Vista won't run any of my software and
nothing else recognizes this hardware", the salesbeing actually suggested
that I download Microsoft's Virual PC thing and run a copy of XP under
that, having Vista talk to the actual hardware. This was apparently a
common problem Best Buy was seeing, and that was the recommended
solution. I paid the 15% restocking fee to give the darn thing back, and
got a Dell preinstalled with Ubuntu, which I've been fairly happy with.

Re: Drivers -- below the OS?

Posted Aug 10, 2007 21:29 UTC (Fri) by heckler (guest, #46684) [Link]

Sadly, I've not read "The Innovator's Dilemma", perhaps I should (nice review by the way)... My overuse of the word value is probably an alliteration thing with virtualization...

The real issue here is, why would an astute technical person purchase such a limited machine from Best Buy? Likewise, why would an astute technical person confuse host based, bare metal based and pv based virtualization? Not to mention a lack of understanding for the architectural differences between where Xen based and the upcoming Viridian hypervisor places and handles drivers, - vs- how something like VMware's ESX handles drivers. In the OS based (Xen/Viridian), all your VMs on a box can get locked via misbehaving driver interaction as you state. Thankfully, with something like ESX that wont happen. As for memory and chopping it in half or writing to the wrong location, have you considered shadow tables, memory overscription and balloon drivers found in some of VMwares products. I'll not go into the elegant stuff they do in ring0, the world switch, and the efforts being done with AMD/Intel in ring-1. Doing so could hamper the growth of some pointy hair on my balding head :-)

> Adding layers neither reduces complexity nor adds stability. It never has.

Never is such a long time when you look backwards. Looking forward, perhaps the days of a bloated Os are coming to a close. Without endorsing it, perhaps some of the "layers" BEA's adding to the stack, owing to virtualization, might give you pause to rethink your statement. (http://www.bea.com/framework.jsp?CNT=index.htm&FP=/co...) In such a stack, I now have a ring-1 perhaps, a virtualization layer, an OS shim within their Liquid VM, a JVM and finally my app. Lots of layers, lots of stability. And its a lot easier to develop apps, debug and admin the system in that environment then when I wrote assembly code, on a microkernel on top of an AN/UYK-20

Lastly, get a MAC and stop dinkering around with dell, HP, etc. Then go get VMware's Fusion for the other 60 or so OSs that product will allow you to run. Perhaps they'll throw in a pre-IPO stock share....

Re: Drivers -- below the OS?

Posted Aug 13, 2007 7:57 UTC (Mon) by himi (guest, #340) [Link]

Virtualization allows IBM to come up with yet more glossy brochures to push mainframes as a replacement for clusters of PCs (although the price of electricity and air conditioning in rackmounted space has been making that case for them for years).

I think this is the thing that makes Linus' comment a bit strong - virtualisation isn't going to revolutionise the way we use computers, but that doesn't mean it's the kind of fad/theoretical ideal/whatever that Linus describes it as. It really does have serious practical uses, and it's important technology. The hype that may be out there about it doesn't invalidate that.

Your point about laptops is excellent, though, and it's one of the reasons I don't see virtualisation becoming the norm outside of server rooms - it makes demands on the system (and on the administrator) that aren't practical in the normal computing space. I've deployed Xen for production infrastructure, but it's never been worth the trouble to use it anywhere else.

himi