Hi, Dave,
It is the explanation that is inaccurate; I was still thinking about mmap when the new paradigm is to do the mapping when the VM faults.
I believe the code that requires this patch is: ttm/ttm_bo_vm.c: ttm_bo_vm_fault(), specifically:
for (i = 0; i < TTM_BO_VM_NUM_PREFAULT; ++i) { if (bo->mem.bus.is_iomem) pfn = ((bo->mem.bus.base + bo->mem.bus.offset) >> PAGE_SHIFT) + page_offset; else {
The "pfn" needs to reflect the correct system bus address to get to the VRAM on the graphics card.
I will rework the commentary and resend.
Thanks for the feedback.
Jay
On 06/13/2011 07:35 PM, Dave Airlie wrote:
On Fri, Jun 10, 2011 at 8:20 AM, Jay Estabrook jay.estabrook@gmail.com wrote:
Alpha needs to have the system bus address for the device's local memory available, so that it can be returned to user-level, where it may be used in an mmap(). So, we make bus.addr hold the ioremap() return for kernel use, and then we can modify bus.base appropriately.
I don't get this. why is mmap passing in an address? we don't do that anymore.
When you mmap the device node it passes back a hashed offset in the table, that the kernel then translates into a proper address and sets up the page tables.
So I really don't get what this patch is doing, either the explaination of what it is doing is wrong or it is wrong.
Dave.