Charlie Jenkins charlie@rivosinc.com writes:
On Fri, Sep 06, 2024 at 04:59:40PM +1000, Michael Ellerman wrote:
Charlie Jenkins charlie@rivosinc.com writes:
Create a personality flag ADDR_LIMIT_47BIT to support applications that wish to transition from running in environments that support at most 47-bit VAs to environments that support larger VAs. This personality can be set to cause all allocations to be below the 47-bit boundary. Using MAP_FIXED with mmap() will bypass this restriction.
Signed-off-by: Charlie Jenkins charlie@rivosinc.com
include/uapi/linux/personality.h | 1 + mm/mmap.c | 3 +++ 2 files changed, 4 insertions(+)
diff --git a/include/uapi/linux/personality.h b/include/uapi/linux/personality.h index 49796b7756af..cd3b8c154d9b 100644 --- a/include/uapi/linux/personality.h +++ b/include/uapi/linux/personality.h @@ -22,6 +22,7 @@ enum { WHOLE_SECONDS = 0x2000000, STICKY_TIMEOUTS = 0x4000000, ADDR_LIMIT_3GB = 0x8000000,
- ADDR_LIMIT_47BIT = 0x10000000,
};
I wonder if ADDR_LIMIT_128T would be clearer?
I don't follow, what does 128T represent?
Sorry, as Christophe explained it's 128 Terabytes, which is the actual value of the address limit.
I think expressing it as the address value is probably more widely understood, and would also match ADDR_LIMIT_3GB.
Have you looked at writing an update for the personality(2) man page? :)
I will write an update to the man page if this patch is approved!
Yeah fair enough.
My (poorly expressed) point was that trying to describe the flag for the man page might highlight that using the 47BIT name requires more explanation.
cheers