On Tue, Dec 03, 2019 at 11:27:39AM +0100, Gerd Hoffmann wrote: > > > > As a result, we can't use the hard coded IO port 0x3f8 > > > > in SeaBIOS for debugging. Instead, we need read the port base > > > > address from the pci uart's BAR, either an IO BAR, or a 32bit > > > > memory BAR. > > > > > > Ok, but ... > > > > > > > + config DEBUG_SERIAL_PCI_BDF > > > > + depends on DEBUG_SERIAL_PCI_IO || DEBUG_SERIAL_PCI_MEM32 > > > > + hex "Serial port PCI bus/device/function" > > > > > > ... hardcoding the BDF instead isn't that great either. Can't we just > > > find the device while scanning for pci devices? > > > > There might be multiple pci uart devices. > > Which I doubt is actually the case. My guess would be you have a > virtual serial device emulated by ME or something similar for > serial-over-lan console access. And there is exactly one of these > per machine.
In my case they are 3 physical PCI HS-UARTs directly from the SoC(but not inside the ME). > > > So hardcoding the BDF seems to be > > a only solution. > > Why? Just use the first device you find by default. Offering the > option to specify the preferred device in case multiple devices exist > is fine, but I doubt this is needed. > > > Actually this solution is similar to the port based uart( > > hard coding the port) and mmio based uart(hard coding the mmio address). > > Here > > we hard code the pci BDF. > > Well, there is no way to reliable discover classic ioport uarts which > are located behind a isa/lpc bridge, so we have to hardcode the port. > There is no other option. > > PCI devices are discoverable, so we can do better than hardcoding the > bdf. And given that seabios scans the pci bus anyway I think we should > do that. This also allows to specify the preferred device by other > means than the bdf, you could use the PCI ID instead for example. I'm ok to use Base-Class/Sub-Class = 0x07/0x00 to filter out the PCI serial devices and choose the first one as the debug port. However, debug port needs to be enabled early, before seabios scans PCI bus. I think we don't want to scan the pci bus by ourself in src/hw/serialio.c, but it's too late to wait for seabios to scan the bus for us. Please advice a feasible solution. > > cheers, > Gerd > _______________________________________________ SeaBIOS mailing list -- seabios@seabios.org To unsubscribe send an email to seabios-le...@seabios.org
