diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 6 | ||||
| -rw-r--r-- | arch/powerpc/mm/hash_utils_64.c | 15 |
2 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 82b42c958d1c..738bae4a5958 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -920,6 +920,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. dhash_entries= [KNL] Set number of hash buckets for dentry cache. + disable_1tb_segments [PPC] + Disables the use of 1TB hash page table segments. This + causes the kernel to fall back to 256MB segments which + can be useful when debugging issues that require an SLB + miss to occur. + disable= [IPV6] See Documentation/networking/ipv6.txt. diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index b2740c67e172..fab46dbe68b3 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -317,6 +317,15 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend, return ret; } +static bool disable_1tb_segments = false; + +static int __init parse_disable_1tb_segments(char *p) +{ + disable_1tb_segments = true; + return 0; +} +early_param("disable_1tb_segments", parse_disable_1tb_segments); + static int __init htab_dt_scan_seg_sizes(unsigned long node, const char *uname, int depth, void *data) @@ -335,6 +344,12 @@ static int __init htab_dt_scan_seg_sizes(unsigned long node, for (; size >= 4; size -= 4, ++prop) { if (be32_to_cpu(prop[0]) == 40) { DBG("1T segment support detected\n"); + + if (disable_1tb_segments) { + DBG("1T segments disabled by command line\n"); + break; + } + cur_cpu_spec->mmu_features |= MMU_FTR_1T_SEGMENT; return 1; } |