On 8/28/23 1:16 PM, Aneesh Kumar K.V wrote: > With CONFIG_SPARSEMEM disabled the below kernel build error is observed. > > arch/powerpc/mm/init_64.c:477:38: error: use of undeclared identifier > 'SECTION_SIZE_BITS' > > CONFIG_MEMORY_HOTPLUG depends on CONFIG_SPARSEMEM and it is more clear > to describe the code dependency in terms of MEMORY_HOTPLUG. Outside > memory hotplug the kernel uses memory_block_size for kernel directmap. > Instead of depending on SECTION_SIZE_BITS to compute the direct map > page size, add a new #define which defaults to 16M(same as existing > SECTION_SIZE) >
Reported-by: kernel test robot <l...@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202308251532.k9ppwead-...@intel.com/ > Fixes: 4d15721177d5 ("powerpc/mm: Cleanup memory block size probing") > Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com> > --- > arch/powerpc/mm/init_64.c | 19 +++++++++++++++---- > 1 file changed, 15 insertions(+), 4 deletions(-) > > diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c > index fcda46c2b8df..e3d7379ef480 100644 > --- a/arch/powerpc/mm/init_64.c > +++ b/arch/powerpc/mm/init_64.c > @@ -472,12 +472,23 @@ static int __init dt_scan_mmu_pid_width(unsigned long > node, > return 1; > } > > +/* > + * Outside hotplug the kernel uses this value to map the kernel direct map > + * with radix. To be compatible with older kernels, let's keep this value > + * as 16M which is also SECTION_SIZE with SPARSEMEM. We can ideally map > + * things with 1GB size in the case where we don't support hotplug. > + */ > +#ifndef CONFIG_MEMORY_HOTPLUG > +#define DEFAULT_MEMORY_BLOCK_SIZE SZ_16M > +#else > +#define DEFAULT_MEMORY_BLOCK_SIZE MIN_MEMORY_BLOCK_SIZE > +#endif > + > static void update_memory_block_size(unsigned long *block_size, unsigned > long mem_size) > { > - unsigned long section_size = 1UL << SECTION_SIZE_BITS; > - > - for (; *block_size > section_size; *block_size >>= 2) { > + unsigned long min_memory_block_size = DEFAULT_MEMORY_BLOCK_SIZE; > > + for (; *block_size > min_memory_block_size; *block_size >>= 2) { > if ((mem_size & *block_size) == 0) > break; > } > @@ -507,7 +518,7 @@ static int __init probe_memory_block_size(unsigned long > node, const char *uname, > /* > * Nothing in the device tree > */ > - *block_size = MIN_MEMORY_BLOCK_SIZE; > + *block_size = DEFAULT_MEMORY_BLOCK_SIZE; > else > *block_size = of_read_number(prop, dt_root_size_cells); > /*
