Benjamin Herrenschmidt wrote:
This fixes radeonfb to not truncate 64 bits resources on 32 bits
platforms. Unfortunately, there are still issues with addresses
returned to userspace via struct fb_fix_screeninfo. This will
have to be dealt with separately.
Thanks for this patch Benjamin, I use it together with what we have discussed in the
"pci issue - wrong detection of pci ressources" thread.
Unfortunately I now hit exactly that issue with fb_fix_screeninfo you describe.
For everyone the fb_fix_screeninfo has two "unsigned long" vars that need to
strore a IO address.
This fails in my case with a 32bit powerpc system (=sizeof(long)=4) which has paddr
>4Gb and actually it should affect any 32bit platform with paddr>4Gb.
You see it e.g. when you try to initialize X11, the x11 radeon driver issues a
FBIOGET_FSCREENINFO ioctl and because our address is >4Gb it get's clobbered by
that unsigned long in the fb_fix_screeninfo structure (the value comes from a
resource_size_t variable which has the correct 64bit).
struct fb_fix_screeninfo {
char id[16]; /* identification string eg "TT Builtin"
*/
unsigned long smem_start; /* Start of frame buffer mem */
[...]
unsigned long mmio_start; /* Start of Memory Mapped I/O */
[...]
I tried the stupid solution to just change the fb_fix_screeninfo structure to
resource_size_t, but that changes the size ioctl transports and would require
awareness in the userspace applications using that ioctl.
The X11 & Framebuffer driver work on 64bit systems, so I think it's just an
issue of not cutting that data down to 32bit when transporting it (has anyone
already checked the x11 drivers, I hope they don't use unsigned long too).
I wanted to ask if there are any known workarounds atm that would allow me to
use my X11 for now?
--
Grüsse / regards,
Christian Ehrhardt
IBM Linux Technology Center, Open Virtualization
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