On Fri, Apr 29, 2016 at 08:54:13AM -0700, Greg KH wrote: > You are trying to take a generalized kernel and somehow "know" about the > hardware ahead of time it is going to run on. That seems like two > conflicting requirements, don't you agree? We would have the 8250 serial port in any kernel. Even if Fedora kernel maintainers allowed us to have specialized kernels for each purpose, I would use the simple ISA serial port here because it allows us to capture debug messages very early in the boot. Alternatives like virtio-console don't allow that. The kernel does know what hardware it's running on - via the CPUID hypervisor leaf. It's also possible for us to tell the kernel about the hardware using the command line, ACPI[*], DT, etc. I'd really like to tell the kernel this is a 16550A, not broken, you don't need to spend time testing that. There is prior art here: no_timer_check & lpj=.. Rich. [*] Although ACPI is really slow, adding another 190ms, and for this reason I have disabled it for now, but not investigated why it's so slow. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org -- 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
