On Thu, 2015-04-16 at 22:17 +0530, Pratyush Anand wrote: > Previous transmission must be completed before next character to be > transmitted, otherwise TX buffer may saturate and we will not see all > the characters on screen. > > @@ -34,6 +38,8 @@ static const char arm64_opts_usage[] __attribute__ ((unused)) = > " --lite Fast reboot, no memory integrity checks.\n" > " --page-offset Kernel page-offset for binary image load.\n" > " --port=ADDRESS Purgatory output to port ADDRESS.\n" > +" --port-lsr=ADDRESS Purgatory output port line status ADDRESS.\n" > +" --port-lsr-val=VALUE Purgatory output port Line status expected SET value when TX empty.\n" > " --ramdisk=FILE Use FILE as the kernel initial ramdisk.\n" > " --reuse-cmdline Use command line arg of primary kernel.\n"; We just need to put some chars to the screen, so I want to avoid a lot of parameters. Usually the status register is at a fixed offset from the TX port. Is that not the case for the ARM uarts? Can't we just poll port-lsr until empty then start writing again? That will at least eliminate port-lsr-val. -Geoff
