[ale] OT: Android native code

[Boris Borisov]

This is very good explanation!

Thank you!


On Sun, Mar 24, 2013 at 3:02 PM, David Tomaschik
<david at systemoverlord.com> wrote:
> On Sun, Mar 24, 2013 at 9:18 AM, Boris Borisov <bugyatl at gmail.com> wrote:
>>
>> My latest device that I bought from BigLots is cheap tablet 4" with
>> moderate specification written on the box but in reality the situation
>> is different. As I mentioned in previous post some of the RAM is
>> locked so there is only 340 MB available. CPU claims 1 Ghz but
>> actually Android uses between 500 and 800 Mhz. Third thing is the SoC
>> itself. Is not one of the ARM cores it is MIPS 74Kc something with no
>> FPU so there is software FPU running by Linux kernel. I don't mind all
>> issues but the latest is little frustrating. I have tried to download
>> pocket version of Minecraft game ( Yes I have two kids ) and Android
>> warned me " Portion of the game contain native code so it may not run
>> at all on this system" . So it does not run :)
>>
>> This is not really a question but just thought. Isn't that some kind
>> of security issue for Android, running native code, isn't that code
>> running outside Dalvik VM. And using native code rejects all other
>> platforms but ARM ...
>
>
> The Android NDK (https://developer.android.com/tools/sdk/ndk/index.html)
> exposes selected Android APIs to run in native code which offers the ability
> to reuse existing C code for CPU-intensive operations on Android.  NDK
> itself supports ARM, x86, and MIPS instruction sets, but each NDK library
> obviously only works with one platform (and sometimes only specific versions
> of that platform).  If the MIPS CPUs had the capabilities Minecraft needed
> and the developers were interested in targeting MIPS, they could build MIPS
> NDK libraries and ship them in the app as well.  According to the Android
> security documentation (http://source.android.com/tech/security/): "Android
> Application Runtime: Android applications are most often written in the Java
> programming language and run in the Dalvik virtual machine. However, many
> applications, including core Android services and applications are native
> applications or include native libraries. Both Dalvik and native
> applications run within the same security environment, contained within the
> Application Sandbox."  In other words, the Android kernel enforces the
> sandbox on applications, rather than depending on the Dalvik VM.
>
> [Obligatory disclaimer since we're discussing Android: I work for Google and
> the views represented here are my own and do not represent Google.  Also,
> for what it's worth, I don't work on Android and this is all just from my
> understanding from playing around with the Android SDK.]
>
>
> --
> David Tomaschik
> OpenPGP: 0x5DEA789B
> http://systemoverlord.com
> david at systemoverlord.com
>
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