On Tue, Oct 6, 2015 at 11:04 AM, Yann Droneaud <ydroneaud@xxxxxxxxxx> wrote:
Hi,
Le mardi 06 octobre 2015 à 10:46 -0400, Kenneth Adam Miller a écrit :
> Let me be more precise in general to the overall original question:
>
> I want a userland process that I designate to only use a specific
> hard coded region physical of memory for it's heap. A UIO driver is
> the means by which I've gone about seeking to achieve this.
>
You want brk() and mmap(..., MAP_ANONYMOUS, ...) to allocate pages
from a contigous physical memory region.
You don't give the reason for such requirement. Without a proper reason
it's difficult to understand what's your trying to achieve.
I can only propose you to use something like CONFIG_MMU=n, but as it's
a system wide choice with multiple drawbacks, I don't think it's
something you want to investigate into.
At our workplace, we are using separation kernel and software fault isolation technologies to trap process capabilities down to specific limitations. With these technologies, we can basically trigger the failure of a process if it tries to violate the sandbox. A process subverting the kernel doesn't make a difference because our enforcement mechanisms preside beneath even that. I can't say much else about why, but using a UIO approach is very attractive to us because we can then develop our IRM in userland, and have actual writes and operations mapped to the address they need to be. Right now that is not the case for our legacy software.
Regards.
--
Yann Droneaud
OPTEYA
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