On 3/24/21 5:34 PM, Dave Hansen wrote:
On 3/24/21 3:05 AM, Thomas Hellström (Intel) wrote:
Yes, I agree. Seems like the special (SW1) is available also for huge
page table entries on x86 AFAICT, although just not implemented.
Otherwise the SW bits appear completely used up.
Although the _PAGE_BIT_SOFTW* bits are used up, there's plenty of room
in the hardware PTEs. Bits 52->58 are software-available, and we're
only using 58 at the moment.
We also have not been careful at *all* about how _PAGE_BIT_SOFTW* are
used. It's quite possible we can encode another use even in the
existing bits.
Personally, I'd just try:
#define _PAGE_BIT_SOFTW5 57 /* available for programmer */
OK, I'll follow your advise here. FWIW I grepped for SW1 and it seems
used in a selftest, but only for PTEs AFAICT.
Oh, and we don't care about 32-bit much anymore?
/Thomas
