Hi, Could you tell me why did you not implement domains in RT kernel version? Are there any difficulties? I'm going to add support of domains, and at the first sight I don't see any difficulties.
Hi, For the first release of the RT kernel (which is a pre-release) we excluded the domain scheduler to make development easier. The final version of the RT kernel will probably include the domain scheduler. However, it should be noted that if using RT + domain scheduler the max deadline miss time is the length of the longest domain, as domains are not pre-emptible. Cheers, Anna. From: Devel [mailto:devel-bounces@sel4.systems] On Behalf Of rad021993@yandex.ru Sent: Tuesday, 21 February 2017 5:01 AM To: devel@sel4.systems Subject: [seL4] RT and domains Hi, Could you tell me why did you not implement domains in RT kernel version? Are there any difficulties? I'm going to add support of domains, and at the first sight I don't see any difficulties.
On 21 Feb 2017, at 10:57, Anna.Lyons@data61.csiro.aumailto:Anna.Lyons@data61.csiro.au wrote: For the first release of the RT kernel (which is a pre-release) we excluded the domain scheduler to make development easier. The final version of the RT kernel will probably include the domain scheduler. However, it should be noted that if using RT + domain scheduler the max deadline miss time is the length of the longest domain, as domains are not pre-emptible. Further to what Anna says, it is unclear (to me at last) whether there are any realistic use cases of real-time systems that would work with the domain scheduler. The whole idea of maintaining confidentiality and timeliness at the same time requires some serious thinking, which I’m not aware of having happened. Absent that, you need to assume that the two are incompatible. And we certainly make no claims that our kernel (once mixed-criticality support is merged with master) is in any way able to support both at the same time. If anyone knows better, I’d love to hear about it. Gernot
Anna, Gernot, thank you for your answers. I want to add domains as analogues to arinc-653 partitions. I know that there will be some time restrictions, but the main goal is compliance with functional requirements of the standard. From: gernot.heiser@data61.csiro.au Sent: Tuesday, February 21, 5:00 AM Subject: Re: [seL4] RT and domains To: devel@sel4.systems On 21 Feb 2017, at 10:57, Anna.Lyons@data61.csiro.au wrote: For the first release of the RT kernel (which is a pre-release) we excluded the domain scheduler to make development easier. The final version of the RT kernel will probably include the domain scheduler. However, it should be noted that if using RT + domain scheduler the max deadline miss time is the length of the longest domain, as domains are not pre-emptible. Further to what Anna says, it is unclear (to me at last) whether there are any realistic use cases of real-time systems that would work with the domain scheduler. The whole idea of maintaining confidentiality and timeliness at the same time requires some serious thinking, which I’m not aware of having happened. Absent that, you need to assume that the two are incompatible. And we certainly make no claims that our kernel (once mixed-criticality support is merged with master) is in any way able to support both at the same time. If anyone knows better, I’d love to hear about it. Gernot
participants (3)
-
Anna.Lyons＠data61.csiro.au -
Gernot.Heiser＠data61.csiro.au -
rad021993＠yandex.ru