On Feb 16, 2012, at 6:10 AM, Li Yang wrote: > Fix the problem that large physical address support cannot be > disabled when some platforms which only provides 36-bit support > are selected. According to the philosophy of kernel config > enabling a platform support doesn't mean the kernel is only > running on that platform. Remove the auto selection of PHYS_64BIT > option for these platforms. They will need to use a 36bit default > config that selects PHYS_64BIT explicitly. > > The reason why we need to keep PHYS_64BIT option configurable is > that enabling it cause negative performance impact on various > aspects like TLB miss and physical address manipulating. We should > not enable it unless really needed, e.g. use large memory of 4GB > or bigger. > > Signed-off-by: Li Yang <le...@freescale.com> > --- > arch/powerpc/platforms/85xx/Kconfig | 6 ------ > 1 files changed, 0 insertions(+), 6 deletions(-)
Nak, this isn't correct. For some of these platforms like P2041RDB, P3041DS, P3060QDS, P4080DS, & P5020DS only a 36-bit physical address map is supported by u-boot and the device tree. This was a decision that was made to NOT support 32-bit address map for these boards and accept the performance implication of it to reduce the # of builds, etc. Additionally, outside of maybe P2041RDB I believe the majority of these boards ship with 4G of DDR (but that off the top of my head) and thus require the 36-bit / PHYS_64BIT support to be enabled. - k _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
