Hi, we came across two functions (read/write) that are defined in the l4 base API documentation: https://os.inf.tu-dresden.de/L4Re/doc/group__l4__mem__op__api.html 1) What does the description "functionality to access user task memory from the kernel" mean? This could be interpreted as accessing user-space memory from within the kernel?! 2) Are there any equivalent memory read/write functions inside the l4re that also take a virtual address as a parameter? To clarify, all intended operations (read/write) should not modify user-space memory from inside the kernel or vice versa. User-space defined read/write functions should operate in user-space exclusively. Best Daniel On 14.02.2017 23:29, Adam Lackorzynski wrote:
Hi,
On Tue Feb 14, 2017 at 10:38:26 +0100, Daniel Krefft wrote:
while working on a checkpoint/restore mechanism for fiasco.oc, we want to trace read and write (kernel) calls to (virtual) memory.
1) Where are these calls defined? We're just able to find ARM specific calls inside the kernel, which allow writing and reading to/from a virtual address
2) Are these calls (if existent) platform agnostic (user-space)? Is there any kind of interface?
I do not quite get the question. The kernel (Fiasco) is running in virtual memory, also when running in the kernel, i.e. any load/store operation that is in the code is through virtual memory. Do you want to trace any read/write issued by the kernel to user-level memory? I'm afraid, the kernel does not do that, i.e. it never touches user-level memory (except the specially treated UTCB memory). Could you please describe your question more verbosely?
Adam
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-- Daniel Krefft MSc. Wissenschaftlicher Mitarbeiter Technische Universitaet Muenchen Fakultaet fuer Informatik Lehrstuhl fuer Betriebssysteme Arcisstrasse 21 80333 Muenchen Tel. +49 89 289 18791 daniel.krefft@tum.de www.os.in.tum.de/personen/krefft