Interface for Kernel Extensions

Hi,

I understand Kernel Extenstions doesn't export any functions to user side. =
my questions are,

1. In case to test screen driver API, how it will be accessed from user sid=
e not like HAL ?

2.In case of testing MMC driver, i have seen OMAP reference they have writt=
en MMC interface for user side commucation like RMMCInf derived from RBusLo=
gicalChannel.

So it mean if user side code wants to access kernel extentions either it ne=
eds LDD or Interface to expose. Is it correct?

Thanks in Advance.

Cheers!
Saravana.

Hi,

Part Answer.

For MMC testing there is a test program MMCTEST, that will connect directly=
to you driver and perform power up/down and sector reads/writes for testin=
g your driver, before trying to use F32 to access the media.

Mark
Symbian

My Question is how to expose API's from kerenel extensions?

1. May be develop interface
2. Devlep Some LDD to expose.



Cheers!


SAravana

Hi,

The MMCTEST program does include an LDD/PDD to access the kernel extension,=
so this can be expanded to other extensions.

Do you have the code for the E32 & F32 tests ?, as these contain code used =
to test the components within the Symbian OS

Mark
Symbian

Hi Saravana,

Kernel extensions and device drivers are differnet.
Kernel extension have layers like PSL/PIL {color:#000000}([Platform=20
independent layer /|MMC_Port.guide.html#Porting%2ddetail%2emmc%2esource%2do=
rg%2epil|Porting detail: MultiMediaCard (MMC) controller / Source organisat=
ion / Platform independent layer]
[Platform=20
specific layer|MMC_Port.guide.html#Porting%2ddetail%2emmc%2esource%2dorg%2e=
psl|Porting detail: MultiMediaCard (MMC) controller / Source organisation /=
Platform specific layer]){color}. As Device drivers are having LDD/PDD.

Can follow "Symbian OS Internals" & "DDK sdk" for more details regarding ap=
i's and differences between them.


Have a nice time

A normal kernel extension would have a single entry point created using the=
DECLARE_STANDARD_EXTENSION
macro.

You can however combine the functions of a driver and a kernel extension in=
a single binary by declaring a second entry point using either DECLARE_EXT=
ENSION_LDD (which is used in the same way as DECLARE_STANDARD_LDD) or DECLA=
RE_EXTENSION_PDD. In this case, you would also need to change the target ty=
pe in your mmp file .LDD/.PDD and use extension\[VARID\]=3D in your oby fil=
e.

See » Symbian OS v9.3 » Device Driver Guide » Symbian OS=
device driver model in the OS library for more explanation. What is it you=
are trying to do?

Edited by: ThingOnASpring on 07-Mar-2008 15:02

Edited by: ThingOnASpring on 07-Mar-2008 15:02

Edited by: ThingOnASpring on 07-Mar-2008 15:02

I have a similar question :

Can kernel extensions have a user level interface ?

In my current implementation access to the I2C bus is via a kernel extensio=
n.
I need to read/write to the I2C bus from a user level application (don't as=
k why .. I just have to ;-)) ...

Do I have to rewrite the I2c as a device driver and then provide user level=
access via the LDD or is there another option of providing some kind of ha=
rdware abstraction layer for kernel extensions ?

I tried reading through the Extensions section in the Symbian OS Internals =
book .. but couldn't quite figure this out.

Thanks.

Hi,

Since the behavior you mention is in most aspects similar to that of user a=
pplication accessing a kernel level resouerce, it makes more sense to do it=
as an LDD module.

Regards
Kozak

hi,
you could not access the extension directly from the user side.

there are 2 methods:

1. you must provide a ldd used by the RBusLogicalChannel derived class. the=
n you can access the driver by this way.
2.through the hal function.

/hzl