what’s the difference between ashmem and FRAMEBUFFER memory?

[Xing Xu]

I understand that there two kinds of GraphicBuffer here for qcom/msm chip: PRIV_FLAGS_FRAMEBUFFER and PRIV_FLAGS_USES_ASHMEM. The ASHMEM will be used as the Android client’s Surface memory, and the FRAMEBUFFER will be used as the SurfaceFlinger’s render target. But when the HWC is enabled, some of the Surface’s memory(from ashmem) will be delivered to HWC.  So does this means both the FRAMEBUFFER memory and Surface memory (ashmem) are treated the same way for the HWC?

If so, what’s the difference between ashmem and FRAMEBUFFER memory?

Any hints will be thankful!