2010/3/12 Kevin O'Connor <ke...@koconnor.net>: > On Thu, Mar 11, 2010 at 03:42:28PM +0800, Roy Tam wrote: >> Sorry I can't find documentation on this usage. But instead I have >> lots of old programs written with this usage. >> Using undocumented features from BIOS/DOS is very usual in that time. > > Can you confirm these other programs fail in the same way (no keyboard > input, and "ps2 irq but no data." messages in log when using > bios.bin-0.5.1-debug-20100228)? > >> > It's broken because it causes key presses to be lost and corrupted. >> > The ps2 port hardware just doesn't work the way that software is >> > trying to use it. >> > >> >> You said that "it causes key presses to be lost and corrupted" but I >> haven't heard any complain about this. >> Real BIOSes (Award BIOS, AMI BIOS, Phoenix BIOS) handle this usage >> very well and no key press are lost or corrupted. > > Under qemu-0.11 normal typing lead to lots of keyboard errors for me. > It's possible real hardware would be less susceptible to this error, > but there is nothing that a BIOS inside qemu can do to stop the > corruption. > >> Any key press should generate 4 IRQs, for example when I press [Tab] >> key, it should have IRQs like this: >> ps2: data f (status=1d) >> ps2: data f (status=1c) >> ps2: data 8f (status=1d) >> ps2: data 8f (status=1c) > > There is one irq on key press and one irq on key release. Your > debugging output is in a loop and you're reporting the same event > twice. > >> The following patch help people to see irq status and data change: > > The current SeaBIOS flow is effectively: > > // Read ps2 port status > u8 status = inb(PORT_PS2_STATUS); > if (!(status & I8042_STR_OBF)) > // No event in queue - nothing can be dequeued. > return; > // Event in queue - dequeue it > u8 data = inb(PORT_PS2_DATA); > // Process the event. > process_ps2byte(status, data); > > Your debugging patch is not correct becuase it performs the event > dequeue before the check to see if there is an event in the queue. >
I don't care about it. As mentioned in OSDEV wiki ( http://wiki.osdev.org/PS2_Keyboard ): Note that if you repeatedly read the port 0x60 without waiting for another IRQ, you'll read the same byte again. That's the 'normal' behaviour of keyboard controller, [...]