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Commite1b385726f("drm/amd/display: Add additional checks for PSP footer size") introduced a use of an uninitialized stack variable in dm_dmub_sw_init() (region_params.bss_data_size). Interestingly, this seems to cause no issue on normal kernels. But when full LTO is enabled, it causes the compiler to "optimize" out huge swaths of amdgpu initialization code, and the driver is unusable: amdgpu 0000:03:00.0: [drm] Loading DMUB firmware via PSP: version=0x07002F00 amdgpu 0000:03:00.0: sw_init of IP block <dm> failed 5 amdgpu 0000:03:00.0: amdgpu_device_ip_init failed amdgpu 0000:03:00.0: Fatal error during GPU init It surprises me that neither gcc nor clang emit a warning about this: I only found it by bisecting the LTO breakage. Fix by using the bss_data_size field from fw_meta_info_params, as was presumably intended. Fixes:e1b385726f("drm/amd/display: Add additional checks for PSP footer size") Signed-off-by: Calvin Owens <calvin@wbinvd.org> Reviewed-by: Harry Wentland <harry.wentland@amd.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Alex Deucher <alexander.deucher@amd.com> (cherry picked from commitb7f1402f6a)
Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. 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