1Tainted kernels 2--------------- 3 4Some oops reports contain the string **'Tainted: '** after the program 5counter. This indicates that the kernel has been tainted by some 6mechanism. The string is followed by a series of position-sensitive 7characters, each representing a particular tainted value. 8 9 1) 'G' if all modules loaded have a GPL or compatible license, 'P' if 10 any proprietary module has been loaded. Modules without a 11 MODULE_LICENSE or with a MODULE_LICENSE that is not recognised by 12 insmod as GPL compatible are assumed to be proprietary. 13 14 2) ``F`` if any module was force loaded by ``insmod -f``, ``' '`` if all 15 modules were loaded normally. 16 17 3) ``S`` if the oops occurred on an SMP kernel running on hardware that 18 hasn't been certified as safe to run multiprocessor. 19 Currently this occurs only on various Athlons that are not 20 SMP capable. 21 22 4) ``R`` if a module was force unloaded by ``rmmod -f``, ``' '`` if all 23 modules were unloaded normally. 24 25 5) ``M`` if any processor has reported a Machine Check Exception, 26 ``' '`` if no Machine Check Exceptions have occurred. 27 28 6) ``B`` if a page-release function has found a bad page reference or 29 some unexpected page flags. 30 31 7) ``U`` if a user or user application specifically requested that the 32 Tainted flag be set, ``' '`` otherwise. 33 34 8) ``D`` if the kernel has died recently, i.e. there was an OOPS or BUG. 35 36 9) ``A`` if the ACPI table has been overridden. 37 38 10) ``W`` if a warning has previously been issued by the kernel. 39 (Though some warnings may set more specific taint flags.) 40 41 11) ``C`` if a staging driver has been loaded. 42 43 12) ``I`` if the kernel is working around a severe bug in the platform 44 firmware (BIOS or similar). 45 46 13) ``O`` if an externally-built ("out-of-tree") module has been loaded. 47 48 14) ``E`` if an unsigned module has been loaded in a kernel supporting 49 module signature. 50 51 15) ``L`` if a soft lockup has previously occurred on the system. 52 53 16) ``K`` if the kernel has been live patched. 54 55The primary reason for the **'Tainted: '** string is to tell kernel 56debuggers if this is a clean kernel or if anything unusual has 57occurred. Tainting is permanent: even if an offending module is 58unloaded, the tainted value remains to indicate that the kernel is not 59trustworthy. 60