Attention is currently required from: Subrata Banik.
Hello build bot (Jenkins), Arthur Heymans,
I'd like you to reexamine a change. Please visit
https://review.coreboot.org/c/coreboot/+/74377
to look at the new patch set (#2).
Change subject: soc/intel/cannonlake: Allow SoC to choose CAR mode (eNEM/NEM) ......................................................................
soc/intel/cannonlake: Allow SoC to choose CAR mode (eNEM/NEM)
This patch avoids cannonlake base config to select eNEM for CAR by default. Rather allow other SoC config to choose the applicable CAR mode between eNEM and NEM.
CML and WHL select eNEM whereas CFL decided to use NEM for CAR setup.
Here is some background about why CFL SoC platform decided to choose NEM over eNEM:
It was found that some coffeelake CPUs like Intel i3 9100E fail to enter CAR mode because some MSR used by NEM enhanced are lacking. According to the Intel SDM CPUID.EAX=07h.ECX=0 reg EBX[12 or 15] should indicate the presence of IA32_PAR_ASSOC and CPUID.EAX=10h.ECX[1 or 2] reg ECX[2] should indicate IA32_L3_QOS_CFG and IA32_L2_QOS_CFG respectively but even on a Intel coffeelake CPU that works with the NEM_ENHANCED these CPUID bits are all 0 so there is no way of knowing whether NEM_ENHANCED will work at runtime. Instead just always use regular NEM.
Signed-off-by: Subrata Banik subratabanik@google.com Change-Id: Ibeaa4d53279ff9cbcd0b2ac5f2ad71925872355b --- M src/soc/intel/cannonlake/Kconfig 1 file changed, 31 insertions(+), 1 deletion(-)
git pull ssh://review.coreboot.org:29418/coreboot refs/changes/77/74377/2