[OpenBIOS] Re: [PATCH] escc: explicitly mark variable containing incoming keyboard character as volatile

[Segher Boessenkool]

On Fri, Oct 25, 2019 at 08:42:13AM +0100, Mark Cave-Ayland wrote:
> On 20/10/2019 13:22, Mark Cave-Ayland wrote:
> > On 18/10/2019 17:23, Segher Boessenkool wrote:
> > unsigned char
> > keyboard_readdata(void)
> > {
> >     volatile unsigned char ch;
> > while (!keyboard_dataready()) { }
> >
> > do {
> >     ch = kbd_dev[2] & 0xff;
> >     if (ch == 99)
> >         shiftstate |= 1;
> >     else if (ch == 110)
> >         shiftstate |= 2;
> >     else if (ch == 227)
> >         shiftstate &= ~1;
> >     else if (ch == 238)
> >         shiftstate &= ~2;
> >     //printk("getch: %d\n", ch);
> > } // If release, wait for key press
> > while ((ch & 0x80) == 0x80 || ch == 238 || ch == 227);
> > //printk("getch rel: %d\n", ch);
> > ch &= 0x7f;
> > if (shiftstate)
> >     ch = sunkbd_keycode_shifted[ch];
> > else
> >     ch = sunkbd_keycode[ch];
> > //printk("getch xlate: %d\n", ch);
> >
> > return ch;
> >
> > }

I don't see how this would loop, given that kbd_dev is a pointer to volatile.
> Any further comments? I'd like to get these last couple of patchsets applied fairly
> soon since it's QEMU freeze starting next week.

I'd use your workaround then?  But something else is going on, it would be
good to figure out what.

Segher