Re: [PATCH v2 2/7] selftests/mm: Add support to test 4PB VA on PPC64

[Donet Tom]

On 7/3/25 8:11 PM, Zi Yan wrote:
> On 3 Jul 2025, at 2:06, Aboorva Devarajan wrote:
>
> > From: Donet Tom <donettom@xxxxxxxxxxxxx>
> >
> > PowerPC64 supports a 4PB virtual address space, but this test was
> > previously limited to 512TB. This patch extends the coverage up to
> > the full 4PB VA range on PowerPC64.
> >
> > Memory from 0 to 128TB is allocated without an address hint, while
> > allocations from 128TB to 4PB use a hint address.
> >
> > Signed-off-by: Donet Tom <donettom@xxxxxxxxxxxxx>
> > Signed-off-by: Aboorva Devarajan <aboorvad@xxxxxxxxxxxxx>
> > ---
> >   tools/testing/selftests/mm/virtual_address_range.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/tools/testing/selftests/mm/virtual_address_range.c b/tools/testing/selftests/mm/virtual_address_range.c
> > index e24c36a39f22..619acf0b9239 100644
> > --- a/tools/testing/selftests/mm/virtual_address_range.c
> > +++ b/tools/testing/selftests/mm/virtual_address_range.c
> > @@ -50,6 +50,7 @@
> >   #define NR_CHUNKS_256TB   (NR_CHUNKS_128TB * 2UL)
> >   #define NR_CHUNKS_384TB   (NR_CHUNKS_128TB * 3UL)
> >   #define NR_CHUNKS_3840TB  (NR_CHUNKS_128TB * 30UL)
> > +#define NR_CHUNKS_3968TB  (NR_CHUNKS_128TB * 31UL)
> >
> >   #define ADDR_MARK_128TB  (1UL << 47) /* First address beyond 128TB */
> >   #define ADDR_MARK_256TB  (1UL << 48) /* First address beyond 256TB */
> > @@ -59,6 +60,11 @@
> >   #define HIGH_ADDR_SHIFT 49
> >   #define NR_CHUNKS_LOW   NR_CHUNKS_256TB
> >   #define NR_CHUNKS_HIGH  NR_CHUNKS_3840TB
> > +#elif defined(__PPC64__)
> > +#define HIGH_ADDR_MARK  ADDR_MARK_128TB
> > +#define HIGH_ADDR_SHIFT 48
> > +#define NR_CHUNKS_LOW   NR_CHUNKS_128TB
> > +#define NR_CHUNKS_HIGH  NR_CHUNKS_3968TB
> >   #else
> >   #define HIGH_ADDR_MARK  ADDR_MARK_128TB
> >   #define HIGH_ADDR_SHIFT 48
> Could you also update the comment above this code to say PowerPC64 also
> supports 4PB virtual address space?


Sure. I will add


>  From the comment, arm64 supports 4PB but its NR_CHUNKS_HIGH is only 3840TB,
> whereas PowerPC64 here can get to 3968TB. I do not know why arm64’s
> 4PB is smaller. ;)
>
> Otherwise, the patch looks good to me.
>
> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
>
> Best Regards,
> Yan, Zi