On Sun, Apr 01, 2018 at 09:11:15AM +0200, Paul Menzel wrote: > Dear Linux folks, > > > The goal is to boot a *distribution* Linux kernel as fast as possible. (The > goal is currently 500 ms.) What distro? > With Linux 4.16-rc7, `serial8250_init()` takes almost 34 ms according to > `initcall_debug` on the laptop TUXEDO Book BU1406 with an Intel Kaby Lake > processor. > > ``` > [ 2.657950] calling serial8250_init+0x0/0x168 @ 1 > [ 2.657963] Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled > [ 2.692598] initcall serial8250_init+0x0/0x168 returned 0 after 33820 > usecs > ``` > > One problem is, that the distributions do not build this as a module, > despite more and more devices do not actually have serial connectors, but > the chipset still exposes them. Then fix that in the distro kernel build. > What options are there? File a bug with the distro. > 1. Try to probe it asynchronously as in the attached patch, which is not > tested yet. Please test it and watch to see what breaks :) good luck! greg k-h -- 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
