[GSoC] UEFI framebuffer task

Sebastian Sumpf Sebastian.Sumpf at ...1...
Sat Mar 25 09:40:04 CET 2017

Hi Philipp,

On 03/24/2017 09:47 AM, Philipp Kerling wrote:
> Hi,
> 2017-03-21 (火) の 10:49 +0100 に Sebastian Sumpf さんは書きました:
>>> Do you have any specific feature
>>> requests besides simple read/write? 
>> Read/write with native command queuing support would suffice.
> NCQ isn't directly applicable to NVMe, at least not in the SATA sense.
> NVMe has mandatory support for 65535 distinct submission queues into
> which you can each put 65536 commands that are executed in no
> particular order (i.e.  possibly in parallel and as the controller sees
> fit, similarly to NCQ).
> For Genode, using one queue would probably be sufficient.
> This does mean that the NVMe driver has to make sure that if you e.g.
> get a write and then a read of the same address queued from an
> application, the read would have to be postponed until the write is
> completed since the NVMe controller does not guarantee in-order
> execution. Now that I think about it though, this also applies to SATA
> NCQ and is what I guess Ata_driver::overlap_check() is for in the AHCI
> driver.

Good research from your side here.

>> If the above is working, it would be interesting to investigate if
>> there
>> are features Genode could benefit from and maybe implement some.
>> Additionally power management is always a topic.
> Ok thanks, noted. Does Genode have support for ACPI device power state
> switching, particularly Runtime D3?

No, power management is still in its infancy. But this is a topic the
Genode staff will have to work on.

> NVMe also supports elaborate PM, some of which (e.g. automatic PM)
> could easily be integrated. The more involved stuff depends a lot on
> knowing the workload and requirements of the system (i.e. burstiness,
> priority of latency or throughput, ...), but that could be made into
> parameters provided to the driver.

Sounds good, looking forward to your proposal.


Sebastian Sumpf
Genode Labs

http://www.genode-labs.com · http://genode.org

Genode Labs GmbH · Amtsgericht Dresden · HRB 28424 · Sitz Dresden
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