adam.biltcliffe wrote:Do I take it there is no C API for accessing the mailboxes?
No, it is really designed for kernel drivers and bare-metal OS.
Because it requires writes to peripheral registers, it really needs either a kernel driver, or a "mmap" hack.
See vc_mem_update from:
https://github.com/raspberrypi/linux/bl ... 8/vc_mem.c
for an example of using the mailbox channel from a kernel driver.
But you might be better off waiting to see if I do the dispmanx overscan hack.
Or even better, find how to disable overscan on your TV.