[Vm-dev] iPhone security (Re: Squeak + Android and Dalvik!?)
eliot.miranda at gmail.com
Fri Oct 23 16:16:27 UTC 2009
2009/10/23 Göran Krampe <goran at krampe.se>
> Hi all!
> Some interesting points:
> On Android you can install an app just by clicking on it in the web browser
> and bam, it will install. AND it can contain native libraries in C or
> whatever BUT AFAICT it needs to "be" a Dalvik Java app around it.
> For example, someone just published Quake wrapped in a very thin
> Java/Dalvik layer around Quake as a C lib working using OpenGL ES.
> THUS... Android is MUCH more fun for Squeak. There is no central bottleneck
> like the App store.
> Secondly, there are TONS of Android phones coming out the next few months.
> The one that most waits for is "The Droid" from Motorola (Motorola is going
> "all in" on Android):
> They take iPhone head on :)
> Note also that the Mono folks are all over Android now, the mono JIT seems
> to run fine, see below.
> Finally, some links:
Goran, thanks for this link. In particular this is a neat idea:
I believe you didn't understand Dan's presentation after all.
The Android security model imposes that each application runs
in its own isolated process, which forces you to implement
one-whole-VM per process runtime model. In case you don't
realize this, this is different from AppDomain because it
allows, among other things, your application to run arbitrary
native code without risking compromising the system's security.
Dalvik is thus designed to share as much code *and* data as
possible between processes. That's why there is an initial
"zygote" process that loads a very large number of system classes
at boot time (where loading each class requires running code
and allocating objects in the heap), which is later forked with
copy-on-write semantics when a new application needs to start.
Consequently, this speeds up the startup of new applications
I don't think Mono supports any of that.
Finally, Dalvik design doesn't preclude a JIT, it's just that
this is not necessary for a large number of applications and
that having a really good interpreter was more important to
ship a 1.0 device.
January 6, 2009 2:15
> Note that Dan Bernstein (designer of Dalvik?) comments it below.
> regards, Göran
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