Upgrade to 15.11 from 15.02 results in quota exceded message

robjsstewart at ...9... robjsstewart at ...9...
Sat Dec 12 19:52:07 CET 2015

The issue with the pwm driver was due to the changes in Attached_io_mem_dataspace introduced in 15.11. 

On the AM335x there are three pwm subsystems whose registers do start on page boundaries and are page sized. Additionally, however, there are three modules within each subsystem each taking up 128 bytes for their registers. (I'd forgotten this fact until i re-read the code i wrote over a year ago.) One of these modules is the ePWM which controls the output of PWM pulses on an io pin. My pwm driver accesses both a subsystem and its ePWM module. In 15.02 I mapped the ePWM registers using the modules address (and the subsystem size, incorrectly) and used offsets to the ePWM module register starting at the subsystems start address. This worked because the actual register space made accessible was the full subsystems page. In 15.11 giving Attached_io_mem_dataspace object constructor the address of the module (and the module size) gives access starting at the module registers. Using the module register offsets used in 15.02 will now be wrong as they are based on the subsystem registers starting address. The correction is simply to zero-base the module register offsets and set the correct size, the module size.

Now everything in my scenario works on 15.11.

Thanks for the help, Martin.


Sent from my android device.

-----Original Message-----
From: robjsstewart at ...196...
To: Genode OS Framework Mailing List <genode-main at lists.sourceforge.net>
Sent: Sat, 05 Dec 2015 11:50 AM
Subject: Re: Upgrade to 15.11 from 15.02 results in quota exceded message

Thanks for following up on this Martin.

I did notice the changes to interrupt handling and updated my drivers accordingly, including the initial ack...interrupts are working well in my 15.11 code.

The io mapping changes I was referring to were in Attached_io_mem_dataspace where sub page handling is apparently is now managed at the byte and not page level. After reading the notes I realized that all the device registers in my platform start on a 4K boundary and also end on one. So that idea went nowhere!

I put a 'scope on several of the pins outputting the PWM signal. To my surprise the pulses were present and their width did change correctly as the driver code altered the duty cycle values, identical to the behavior on 15.02. The compiler did change between 15.02 and 15.11 and this leads me to think I may have some poor code design in my pwm device driver causing a race condition during the set up of the pwm subsystem or the pwm channels...a timing change due to the different compiled code could expose such an issue. My current belief is that the ESC is being reset after set up or because of some wrong sequence during set up. The ESC's emit audible tones when they receive initial pulses after power on and there are differences between the tones emitted between the 15.02 version and 15.11. 

I'm ok with sharing my code but I think the hardware is needed to really debug this issue. Every other piece of code in this scenario works as it did in 15.02 including gpio output to status leds and pwm inputs on gpio pins.

I'll keep you posted as I progress.

Sent from my android device.

-----Original Message-----
From: Martin Stein <martin.stein at ...1...>
To: Genode OS Framework Mailing List <genode-main at lists.sourceforge.net>
Sent: Sat, 05 Dec 2015 10:10 AM
Subject: Re: Upgrade to 15.11 from 15.02 results in quota exceded message

Hi Bob,

Am 03.12.2015 um 13:37 schrieb Bob Stewart:
> The scenario I run includes sdcard, gpio, gp timers, uarts, i2c, and PWM
> drivers and vfs is also in there. All of this, with my modified base-hw
> kernel, appears to be running as it does in 15.02 with the exception of
> the PWM driver. The log from the 15.11 implementation shows nothing
> exceptional (attached) and is practically identical to what is output on

While reading this, it came to my mind that somewhere around the
beginning of the year, interrupt semantics have changed on base-hw. In
the past, an IRQ session, once opened, directly started handling
interrupts. Today, the handling, and therefore also the reception, of
interrupts doesn't start until an initial 'Irq_session::irq_ack' call. I
know, its a shot in the dark. But just to be sure you may check whether
your drivers already send this initial ack.

> 15.02. Running my PWM driver in verbose mode shows that data received
> from sensors on the i2c bus and from a manual input controller is being
> correctly received, processed, and sent to the PWM driver. The PWM does
> some signal conditioning and writes updated duty cycle values to an IO
> register from which the SoC's pwm subsystem sends the modified pulse to
> an IO pin. That pin is attached to a motor ESC which provides the power
> to drive the motor. The motor never receives the pulse. So, presumably,

My first intention is, that this could also be a bad GPIO configuration.
However, with the information I have this can only be a vague guess. Can
you share your source code including the run script that you're using?
Most comfortable would be an on-line git branch :)

> there is an issue with IO mapping and the signal is not going to the
> correct register location. I notice in the 5.11 release notes that there
> have been changes in the area of memory mapped IO, so I'm starting to

Sorry, I'm afraid that I do not know which changes you mean. Could you
please go in more detail?

> explore that avenue. I have not touched the PWM driver code in more than
> a year so I doubt that the problem is there.


Go from Idea to Many App Stores Faster with Intel(R) XDK
Give your users amazing mobile app experiences with Intel(R) XDK.
Use one codebase in this all-in-one HTML5 development environment.
Design, debug & build mobile apps & 2D/3D high-impact games for multiple OSs.
genode-main mailing list
genode-main at lists.sourceforge.net
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.genode.org/pipermail/users/attachments/20151212/3fb8a30b/attachment.html>

More information about the users mailing list