2016-04-29 1:18 GMT+03:00 Richard W.M. Jones <rjones@xxxxxxxxxx>: > [This is an opinionated patch, mainly for discussion.] > > I'm trying to reduce the time taken in the kernel in initcalls, with > my aim being to reduce the current ~700ms spent in initcalls before > userspace, down to something like 100ms. All times on my Broadwell-U > laptop, under virtualization. The purpose of this is to be able to > launch VMs around containers with minimal overhead, like Intel Clear > Containers, but using standard distro kernels and qemu. > > Currently the kernel spends 25ms inspecting the UART that we passed to > it from qemu to find out whether it's an 8250/16550/16550A perhaps > with a non-working FIFO or other quirks. Well, it isn't -- it's a > working emulated 16550A, with a FIFO and no quirks, and if it isn't, > we should fix qemu. > > So the patch detects if we're running virtualized (perhaps it should > only check for qemu/KVM?) and if so, shortcuts the tests. Does anybody know, whether it is possible to pass through real hardware serial port to a guest? It seems to be as simple as to pass through an interrupt and memory IO ports. > > Rich. > -- With best regards, Matwey V. Kornilov. Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia 119991, Moscow, Universitetsky pr-k 13, +7 (495) 9392382 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
