xf86-video-mga: Changes to 'master'

[GitLab Mirror]

 src/mga_exa.c |   18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

New commits:
commit a939aa56b3af4418d0c026a3775fde7288b0cca7
Author: Mikulas Patocka <mikulas at twibright.com>
Date:   Tue Nov 20 08:41:14 2018 -0800

    mga_drv: fix image corruption due to memcpy reordering
    
    The memcpy specification doesn't specify how the destination is written -
    and on glibc 2.19 memcpy is doing some bytewise writes with the rep stosb
    instruction. These bytewise writes confuse the hardware (because it
    expects 32-bit writes) and result in image corruption.
    
    This patch replaces memcpy with explicit writes, so that the sequential
    write order and 32-bit write size is guaranteed. We use the "volatile"
    attribute to make sure that compiler optimizations won't cause write
    reordering. When reading the memory, we use a structure with "packed"
    attribute to avoid unaligned traps on RISC machines.
    
    Tested-by: Kevin Brace <kevinbrace at gmx.com>
    Signed-off-by: Mikulas Patocka <mikulas at twibright.com>