• Maciej W. Rozycki's avatar
    [MIPS] R4000/R4400 errata workarounds · 20d60d99
    Maciej W. Rozycki authored
     This is the gereric part of R4000/R4400 errata workarounds.  They include 
    compiler and assembler support as well as some source code modifications 
    to address the problems with some combinations of multiply/divide+shift 
    instructions as well as the daddi and daddiu instructions.
     Changes included are as follows:
    1. New Kconfig options to select workarounds by platforms as necessary.
    2. Arch top-level Makefile to pass necessary options to the compiler; also 
       incompatible configurations are detected (-mno-sym32 unsupported as 
       horribly intrusive for little gain).
    3. Bug detection updated and shuffled -- the multiply/divide+shift problem 
       is lethal enough that if not worked around it makes the kernel crash in 
       time_init() because of a division by zero; the daddiu erratum might 
       also trigger early potentially, though I have not observed it.  On the 
       other hand the daddi detection code requires the exception subsystem to 
       have been initialised (and is there mainly for information).
    4. r4k_daddiu_bug() added so that the existence of the erratum can be 
       queried by code at the run time as necessary; useful for generated code 
       like TLB fault and copy/clear page handlers.
    5. __udelay() updated as it uses multiplication in inline assembly.
     Note that -mdaddi requires modified toolchain (which has been maintained 
    by myself and available from my site for ~4years now -- versions covered 
    are GCC 2.95.4 - 4.1.2 and binutils from 2.13 onwards).  The -mfix-r4000 
    and -mfix-r4400 have been standard for a while though.
    Signed-off-by: default avatarMaciej W. Rozycki <macro@linux-mips.org>
    Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
Makefile 21.3 KB