Linux 4.0 DSU support is a far cry from supporting Vaughan-Nichols’ hope that “With Linux 4.0, updates to a program we can make statically we can also make dynamically.
I.e., we should be able to add new functions, change function types (e.g., to have new or different arguments), or modify data structures, e.g., by adding new data elements, breaking apart or changing the types of existing elements, adding and removing pointers, etc.
This means that the old version of function setup ran, which did not set the variable global_ptr.
But after the update, the new version of function handle will execute, which will dereference the global variable and crash. That is, when performing a system call, the kernel either executes old code or new code, but not a mix of both.
to switch slides To help keep your version of Opera up-to-date, with the latest features and important security and stability fixes, Opera includes an automatic update mechanism.
The auto-update dialog appears after a recommended update has been released.
In this post, co-authored with my Ph D student Luís Pina, I take a closer look at the challenge that DSU presents, showing that what Linux will support is still quite far from what we might hope for, but that ideas from the research community promise to get us closer to the ideal, both for operating systems and hopefully for many other applications as well. If in the updated program the entries of a hash table are extended with a timeout field, then a dynamic update needs to convert in-memory hashtable entries to now contain a timeout field; otherwise, when the updated code goes to access that field, it will behave unpredictably.
Or, if the new code uses two threads to perform some functionality which in the old version requires only one thread, then we need to map the existing thread’s stack to an equivalent one for the new code, and start a new thread to handle the extracted functionality.
KGraft uses an extra level of indirection called a “reality-check” to decide, at the entry of patched functions, which code to execute based on the process flag.Links added to your document through the link editor, will be overwritten during an update.Only links created in the document using the link creation tool before uploading to issuu, will remain after updating or replacing a publication.KGraft enforces version consistency on a per-process basis, so it is possible for one process to execute the new code while another process executes the old code.When a process makes a system call after the patch is installed, k Graft sets a “new universe” flag on that process.
Once the flag is set on all processes, k Graft drops the now-redundant indirection and jumps straight to the patched code.