diff options
| -rw-r--r-- | sys/amd64/amd64/pmap.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c index caefdea..7aab65b 100644 --- a/sys/amd64/amd64/pmap.c +++ b/sys/amd64/amd64/pmap.c @@ -4984,6 +4984,14 @@ pmap_copy_pages(vm_page_t ma[], vm_offset_t a_offset, vm_page_t mb[], int cnt; boolean_t pinned; + /* + * NB: The sequence of updating a page table followed by accesses + * to the corresponding pages used in the !DMAP case is subject to + * the situation described in the "AMD64 Architecture Programmer's + * Manual Volume 2: System Programming" rev. 3.23, "7.3.1 Special + * Coherency Considerations". Therefore, issuing the INVLPG right + * after modifying the PTE bits is crucial. + */ pinned = FALSE; while (xfersize > 0) { a_pg_offset = a_offset & PAGE_MASK; |
