Hi I tried to use a PCIe graphics card on the MacchiatoBIN board and I hit a strange problem.
When I use the links browser in graphics mode on the framebuffer, I get occasional pixel corruption. Links does memcpy, memset and 4-byte writes on the framebuffer - nothing else. I found out that the pixel corruption is caused by overlapping unaligned stp instructions inside memcpy. In order to avoid branching, the arm64 memcpy implementation may write the same destination twice with different alignment. If I put "dmb sy" between the overlapping stp instructions, the pixel corruption goes away. This seems like a hardware bug. Is it a known errata? Do you have any workarounds for it? I tried AMD card (HD 6350) and NVidia (NVS 285) and both exhibit the same corruption. OpenGL doesn't work (it results in artifacts on the AMD card and lock-up on the NVidia card), but it's quite expected if even simple writing to the framebuffer doesn't work. Mikulas
