On 07/12/2017 08:35 PM, Michael Brown wrote: > On 12/07/17 19:15, Heinrich Schuchardt wrote: >> Nope. Interrupts are not supported by U-Boot. To get them running every >> architecture implementation would have to be changed. >> >> U-Boot simply uses a call inside the waiting loop to check if new data >> is available. >> >> E.g. in UEFI WaitForEvent it will check if new data becomes available on >> the serial console or on the network interface inside a loop. In >> CheckEvent it will do the same. If data becomes available it will fire >> the UEFI event. > > OK. What facility does U-Boot provide to allow the CPU to sleep (i.e. > to allow an idling program to avoid running with 100% CPU usage)?
None. U-Boot loads grub or the OS kernel within a few seconds. So why bother about reducing CPU load of the only core that is running? E.g. on the Davinci boards the waiting routine udelay is implemented using while (get_ticks() < endtime) ; Best regards Heinrich _______________________________________________ ipxe-devel mailing list ipxe-devel@lists.ipxe.org https://lists.ipxe.org/mailman/listinfo.cgi/ipxe-devel