Jakub,
Thanks for following up!
On Friday, 27 August 2021 09:20:35 CEST Jakub Jermář wrote:
On 8/27/21 1:45 AM, Paul Boddie wrote:
Anyway, if anyone has any insight into why the attach operation behaviour is different, I would very much appreciate it!
This behavior was introduced by the following commit in 2019:
https://github.com/kernkonzept/l4re-core/commit/81edd6119c45be6f1448a5535b13 78fbc9ce89b9
New dataspace and region map APIs
The new APIs allow 64bit offsets and size of dataspaces also on 32bit architectures. And have a clean and type-safe dataspace flags and region flags model including execute rights and the possibility of execute-only pages and so on.
Change-Id: I77273a5bb93c9891bca4f848c9b17db332b1b72a
That might seem like a while ago, but I put off migrating to the GitHub repositories for some time, partly due to issues I was having with my increasingly ancient system (it wasn't reliably computing SHA1 digests and thus Git was very unhappy), partly due to inertia and having a stable code base to work with, although I'm obviously having to catch up now.
In general, you must specify the access rights of the attached region explicitly now, otherwise the rights will be --- (empty) and it will not be possible to access the region. Previously the default was RW access.
Is this to expose the rights more obviously to the client, make it "promise" to only access pages in a certain way, and to save the region manager the trouble of sending requests to the dataspace that will only end up being refused?
My workaround for now will be to request read/write access, given that I am merely providing filesystem content to programs, but I guess that if I were to have my dataspaces providing the content of executables, I would need the client program to indicate read/execute access, perhaps. (I'm not at that stage, yet: it's been quite a learning experience.)
This commit broke backwards compatibility in exchange for the benefits described in the commit message. We modified all our repositories to reflect this change back in 2019, but obviously you need to make adaptations to your own code yourself.
Sure. Thanks for confirming what I suspected!
Paul