"Jonathan P. Leech" <jon@cit-vax.ARPA> (11/20/84)
We are running 4.2 on a 780. Recently our system manager implemented a device driver which uses statically allocated RAM to emulate a frame buffer. This works fine, but it would be nice to remove the overhead of system calls on each read/write to the 'frame buffer'. Can anyone tell me how to make kernel memory read and writeable from a normal process? Thanks, Jon Leech jon@cit-vax
Ron Natalie <ron@BRL-TGR.ARPA> (11/20/84)
Add these to the end of uba.c maptouser(vaddress) caddr_t vaddress; { Sysmap[(((unsigned)(vaddress))-0x80000000) >> 9].pg_prot = (PG_UW>>27); } unmaptouser(vaddress) caddr_t vaddress; { Sysmap[(((unsigned)(vaddress))-0x80000000) >> 9].pg_prot = (PG_KW>>27); } and then call them from an IOCTL in the device driver.