UIO Devices and user processes

[Kenneth Adam Miller]

On Tue, Oct 6, 2015 at 11:04 AM, Yann Droneaud <ydroneaud at opteya.com> 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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