On 8/14/18 4:12 AM, Johannes Lundberg wrote:
Hi
Something that we have seen for a long time on FreeBSD is the boot message
Failed to add WC MTRR for [0xd0000000-0xdfffffff]: -22; performance may
suffer
Taking a closer look at this with memcontrol I can see that the 256 MB
region that DRM wants to set as WC is already covered by this entry
0xc0000000/0x40000000 BIOS uncacheable set-by-firmware active
Similar on both my Skylake and Broadwell systems.
I see something similar on my Dell XPS 13 with a Kaby Lake R:
Failed to add WC MTRR for [0x90000000-0x9fffffff]: -22; performance may
suffer
0x80000000/0x80000000 BIOS uncacheable set-by-firmware active
The only mappings in this range are MMIO:
machdep.efi_map:
Type Physical Virtual #Pages Attr
[snip]
MemoryMappedIO 0000e0000000 0xe0000000 00010000 RUNTIME
MemoryMappedIO 0000fe000000 0xfe000000 00000011 UC RUNTIME
MemoryMappedIO 0000fec00000 0xfec00000 00000001 UC RUNTIME
MemoryMappedIO 0000fee00000 0xfee00000 00000001 UC WT WB WP RUNTIME
MemoryMappedIO 0000ff000000 0xff000000 00001000 UC WT WB WP RUNTIME
Eric
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