On 24/10/2020 21:51, Philippe Mathieu-Daudé wrote: > The S24/TCX datasheet is listed as "Unable to locate" on [1]. > > However the NetBSD revision 1.32 of the driver introduced > 64-bit accesses to the stippler and blitter [2]. It is safe > to assume these memory regions are 64-bit accessible. > QEMU implementation is 32-bit, so fill the 'impl' fields. > > Michael Lorenz (author of the NetBSD code [2]) provided us with more > information in [3]: > >> IIRC the real hardware *requires* 64bit accesses for stipple and >> blitter operations to work. For stipples you write a 64bit word into >> STIP space, the address defines where in the framebuffer you want to >> draw, the data contain a 32bit bitmask, foreground colour and a ROP. >> BLIT space works similarly, the 64bit word contains an offset were to >> read pixels from, and how many you want to copy. >> >> One more thing since there seems to be some confusion - 64bit accesses >> on the framebuffer are fine as well. TCX/S24 is *not* an SBus device, >> even though its node says it is. >> S24 is a card that plugs into a special slot on the SS5 mainboard, >> which is shared with an SBus slot and looks a lot like a horizontal >> UPA slot. Both S24 and TCX are accessed through the Micro/TurboSPARC's >> AFX bus which is 64bit wide and intended for graphics. >> Early FFB docs even mentioned connecting to both AFX and UPA, >> no idea if that was ever realized in hardware though. > > [1] http://web.archive.org/web/20111209011516/http://wikis.sun.com/display/FOSSdocs/Home > [2] http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/dev/sbus/tcx.c.diff?r1=1.31&r2=1.32 > [3] https://