Beginning with version 21, swrast is no more: https://www.phoronix.com/scan.php?page=news_item&px=Mesa-Kills-SWRAST

As a consequence, trying to build mesa with the meta-freescale bbappends and openembedded-core (both latest master) produces this error:

    ../mesa-21.0.1/meson.build:21:0: ERROR: Options "swrast" are not in allowed choices: "auto, i915, i965, r100, r200, nouveau"

Did anybody already look into this? According to the article, swrast was replaced with llvmpipe. It is not clear to me why swrast was ever used, however:

    # For parts with GPU and DRM, use osmesa, dri, and swrast
    PACKAGECONFIG_REMOVE_NXPBSP_imxgpu_imxdrm = "gallium"
    PACKAGECONFIG_APPEND_NXPBSP_imxgpu_imxdrm = "osmesa"
    DRIDRIVERS_NXPBSP_imxgpu_imxdrm           = "swrast"

Why did this need swrast for using DRM?