On Mon, 8 Apr 2024, Florian Weimer wrote:
> * Alexander Monakov: > > >> There is quite a bit of variance in how the kernel is entered. On > >> x86-64, one once popular mechanism is longer present in widely-used > >> kernels. > > > > I assume you're implicitly referencing the vsyscall mechanism, but on > > amd64 it's not useful to *enter the kernel*, right? It was useful for > > obtaining the result of certain syscalls without actually entering > > the kernel, like with vdso. > > The implementation performed a standard system call if a pure userspace > implementation wasn't possible. It wasn't intended as a general-purpose > way to enter the kernel (although it could be used as such, hence the > desire to remove it in some cases). I guess you meant it was "popular" only for the specific syscalls it provided acceleration for. I'm not sure how that is relevant to the current discussion. Alexander
