On Mon, 06 Mar 2017 09:07:48 +0530 "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> wrote:
> "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> writes: > > > Michal Suchánek <msucha...@suse.de> writes: > > > >> Hello, > >> > >> On Sun, 19 Feb 2017 15:37:15 +0530 > >> "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> wrote: > >> > >>> We update the hash linux page table layout such that we can > >>> support 512TB. But we limit the TASK_SIZE to 128TB. We can switch > >>> to 128TB by default without conditional because that is the max > >>> virtual address supported by other architectures. We will later > >>> add a mechanism to on-demand increase the application's effective > >>> address range to 512TB. > >>> > >>> Having the page table layout changed to accommodate 512TB makes > >>> testing large memory configuration easier with less code changes > >>> to kernel > >>> > >>> Signed-off-by: Aneesh Kumar K.V > >>> <aneesh.ku...@linux.vnet.ibm.com> > > > > .... > > > >> index b64daf124fee..c7ca70dc3ba5 100644 > >>> --- a/arch/powerpc/kernel/paca.c > >>> +++ b/arch/powerpc/kernel/paca.c > >>> @@ -253,8 +253,15 @@ void copy_mm_to_paca(struct mm_struct *mm) > >>> get_paca()->mm_ctx_id = context->id; > >>> #ifdef CONFIG_PPC_MM_SLICES > >>> get_paca()->mm_ctx_low_slices_psize = > >>> context->low_slices_psize; > >>> + /* > >>> + * We support upto 128TB for now. Hence copy only 128/2 > >>> bytes. > >>> + * Later when we support tasks with different max > >>> effective > >>> + * address, we can optimize this based on mm->task_size. > >>> + */ > >>> + BUILD_BUG_ON(TASK_SIZE_USER64 != TASK_SIZE_128TB); > >> > >> Can this be handled by KConfig? > >> Above I see > > > > I am reworking the series so that we depend on mm->task_size. Will > > send a new version soon. > > > > > > > >>> +#ifdef CONFIG_PPC_BOOK3S_64 > >>> +#define TASK_SIZE_USER64 TASK_SIZE_128TB > >>> +#else > >>> +#define TASK_SIZE_USER64 TASK_SIZE_64TB > >>> +#endif > >> and > >>> #ifdef CONFIG_PPC_MM_SLICES > >>> ILD_BUG_ON(TASK_SIZE_USER64 != TASK_SIZE_128TB) > >> > >> which boils down to > >> #ifndef CONFIG_PPC_BOOK3S_64 > >> #ifdef CONFIG_PPC_MM_SLICES > >> #error TASK_SIZE_USER64 != TASK_SIZE_128TB > >> > >> > >>> memcpy(&get_paca()->mm_ctx_high_slices_psize, > >>> - &context->high_slices_psize, SLICE_ARRAY_SIZE); > >>> + &context->high_slices_psize, TASK_SIZE_128TB >> > >>> 41); > >> > >> Can we avoid magic numbers, please? > >> > > > > Since array is 4 bytes per each TB which is documented else where. > > 4 bits per teach TB. > It is certainly nicer to have a macro for it. You can then see what the number is from the macro name or grep it and find the definition and the explanation. Thanks Michal
