On 2019-03-26 22:28, Jarkko Sakkinen wrote:
> On Tue, Mar 26, 2019 at 04:58:52PM -0700, Sean Christopherson wrote:
>> On Tue, Mar 26, 2019 at 03:26:50PM +0200, Jarkko Sakkinen wrote:
>>> On Thu, Mar 21, 2019 at 05:51:11PM +0200, Jarkko Sakkinen wrote:
>>>>> Yuck.  If we remove the driver specific Makefile then we can eliminate
>>>>> the "../" prefix here.  E.g. in the main SGX Makefile:
>>>>>
>>>>> obj-$(CONFIG_INTEL_SGX_DRIVER) += driver/main.o driver/ioctl.o
>>>>
>>>> I think this is a great idea.
>>>
>>> On a 2nd thought not gonna do anything to that because it would
>>> require to move driver.h and it is cleaner to keep all the driver
>>> files in the same directory (and separated from the core).
>>
>> What about collapsing driver/*.c into driver.c and moving driver.{c,h}
>> to the root sgx directory?  The bulk of driver/main.c is securityfs
>> and platform driver code, e.g. has a good chance of going away entirely
>> or being moved out of the "driver".  At that point there probably isn't
>> a strong reason to have driver/main.c and driver/ioctl.c.
> 
> I think doing anything major would require to lock in whether to have
> the LKM for the driver at all. If we wipe out the driver, then this is
> just matter of moving dev management part to lets say dev.c.
> 
> Unless there is some real production use I can wipe it away. For v19
> I wanted to fix it namely because in v18 LKM was just broken. It is
> always good to make decisions based on working code.

It should be a module because things should be modules when possible. 
I'm not sure what the "Linux policy" is here but this seems obvious to me.

For example:

* Modules allow users to easily disable functionality that they don't 
use/is buggy for them/other reasons using blacklisting.
* Modules allow users to customize their functionality without having to 
rebuild the entire kernel.
* Modules allow developers to customize their modules without having to 
rebuild the entire kernel.

Specifically for SGX I can think of the following reasons as well:

* Module-based hypervisors may want to make EPC allocations for their 
guests.
* Easy experimentation with different EPC interfaces
* Easy experimentation with in-kernel LE

--
Jethro Beekman | Fortanix

> 
> /Jarkko
>