I went ahead and implemented the "ndmpdpphys" change I
had thought about. Here's that patch by itself.
At this point it might be reasonable to use the patch
without the AMD64_HUGE option, just increasing the KVM
area, as the direct map no longer consumes extra pages.
(There's a glitch in the comment in the original patch,
I'll fix that if/when there's any agreement on whether
it gets applied in some form :-) )
Chris
diff --git a/amd64/amd64/pmap.c b/amd64/amd64/pmap.c
index acf5af2..f1ed8b6 100644
--- a/amd64/amd64/pmap.c
+++ b/amd64/amd64/pmap.c
@@ -232,6 +232,7 @@ u_int64_t KPML4phys; /* phys addr of kernel
level 4 */
static u_int64_t DMPDphys; /* phys addr of direct mapped level 2 */
static u_int64_t DMPDPphys; /* phys addr of direct mapped level 3 */
+static int ndmpdpphys; /* number of DMPDPphys pages */
static struct rwlock_padalign pvh_global_lock;
@@ -543,7 +544,18 @@ create_pagetables(vm_paddr_t *firstaddr)
ndmpdp = (ptoa(Maxmem) + NBPDP - 1) >> PDPSHIFT;
if (ndmpdp < 4) /* Minimum 4GB of dirmap */
ndmpdp = 4;
- DMPDPphys = allocpages(firstaddr, NDMPML4E);
+ ndmpdpphys = howmany(ndmpdp, NPML4EPG);
+ if (ndmpdpphys > NDMPML4E) {
+ /*
+ * Each NDMPML4E allows 512 GB, so limit to that,
+ * and then readjust ndmpdp and ndmpdpphys.
+ */
+ printf("NDMPML4E limits system to %d GB\n", NDMPML4E * 512);
+ Maxmem = atop(NDMPML4E * NBPML4);
+ ndmpdpphys = NDMPML4E;
+ ndmpdp = NDMPML4E * NPDEPG;
+ }
+ DMPDPphys = allocpages(firstaddr, ndmpdpphys);
ndm1g = 0;
if ((amd_feature & AMDID_PAGE1GB) != 0)
ndm1g = ptoa(Maxmem) >> PDPSHIFT;
@@ -626,7 +638,7 @@ create_pagetables(vm_paddr_t *firstaddr)
p4_p[PML4PML4I] |= PG_RW | PG_V | PG_U;
/* Connect the Direct Map slot(s) up to the PML4. */
- for (i = 0; i < NDMPML4E; i++) {
+ for (i = 0; i < ndmpdpphys; i++) {
p4_p[DMPML4I + i] = DMPDPphys + ptoa(i);
p4_p[DMPML4I + i] |= PG_RW | PG_V | PG_U;
}
@@ -1698,7 +1710,7 @@ pmap_pinit(pmap_t pmap)
pmap->pm_pml4[KPML4BASE + i] = (KPDPphys + (i << PAGE_SHIFT)) |
PG_RW | PG_V | PG_U;
}
- for (i = 0; i < NDMPML4E; i++) {
+ for (i = 0; i < ndmpdpphys; i++) {
pmap->pm_pml4[DMPML4I + i] = (DMPDPphys + (i << PAGE_SHIFT)) |
PG_RW | PG_V | PG_U;
}
@@ -1955,7 +1967,7 @@ pmap_release(pmap_t pmap)
for (i = 0; i < NKPML4E; i++) /* KVA */
pmap->pm_pml4[KPML4BASE + i] = 0;
- for (i = 0; i < NDMPML4E; i++) /* Direct Map */
+ for (i = 0; i < ndmpdpphys; i++)/* Direct Map */
pmap->pm_pml4[DMPML4I + i] = 0;
pmap->pm_pml4[PML4PML4I] = 0; /* Recursive Mapping */
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