pc, pc64: allow passing RSDT pointer in *acpi= boot parameter, early bootscreeninit(), fix rampage() usage

rampage() cannot be used after meminit(), so test for
conf.mem[0].npage != 0 and use xalloc()/mallocalign()
instead. this allows us to use vmap() early before
mmuinit() which is needed for bootscreeninit() and
acpi.

to get memory for page tables, pc64 needs a lowraminit().

with EFI, the RSDT pointer is passed in *acpi= parameter
from the efi loader. as the RSDT is ususally at the end of
the physical address space (and not to be found in
bios areas), we cannot KMAP() it so we need to vmap().

sys/src/9/pc/archacpi.c

@@ -645,11 +645,17 @@ readtbls(Chan*, void *v, long n, vlong o)
 static int
 identify(void)
 {
+	uintptr pa;
 	char *cp;
 
 	if((cp = getconf("*acpi")) == nil)
 		return 1;
-	if((rsd = sigsearch("RSD PTR ")) == nil)
+	pa = (uintptr)strtoull(cp, nil, 16);
+	if(pa <= 1)
+		rsd = sigsearch("RSD PTR ");
+	else
+		rsd = vmap(pa, sizeof(Rsd));
+	if(rsd == nil)
 		return 1;
 	if(checksum(rsd, 20) && checksum(rsd, 36))
 		return 1;

sys/src/9/pc/main.c

@@ -146,15 +146,15 @@ main(void)
 	cpuidentify();
 	meminit();
 	confinit();
-	archinit();
 	xinit();
+	archinit();
+	bootscreeninit();
 	if(i8237alloc != nil)
 		i8237alloc();
 	trapinit();
 	printinit();
 	cpuidprint();
 	mmuinit();
-	bootscreeninit();
 	if(arch->intrinit)	/* launches other processors on an mp */
 		arch->intrinit();
 	timersinit();

sys/src/9/pc/mmu.c

@@ -59,7 +59,6 @@ Segdesc gdt[NGDT] =
 [KESEG16]		EXEC16SEGM(0),	/* kernel code 16-bit */
 };
 
-static int didmmuinit;
 static void taskswitch(ulong, ulong);
 static void memglobal(void);
 
@@ -79,8 +78,6 @@ mmuinit(void)
 	ulong x, *p;
 	ushort ptr[3];
 
-	didmmuinit = 1;
-
 	if(0) print("vpt=%#.8ux vpd=%#p kmap=%#.8ux\n",
 		VPT, vpd, KMAP);
 
@@ -523,7 +520,7 @@ mmuwalk(ulong* pdb, ulong va, int level, int create)
 			 * memory.c if we haven't set up the xalloc
 			 * tables yet.
 			 */
-			if(didmmuinit)
+			if(conf.mem[0].npage != 0)
 				map = xspanalloc(BY2PG, BY2PG, 0);
 			else
 				map = rampage();

sys/src/9/pc64/main.c

@@ -32,6 +32,7 @@ int idle_spin;
 uchar *sp;	/* user stack of init proc */
 
 extern void (*i8237alloc)(void);
+extern void bootscreeninit(void);
 
 static void
 multibootargs(void)
@@ -506,8 +507,9 @@ main()
 	cpuidentify();
 	meminit();
 	confinit();
-	archinit();
 	xinit();
+	archinit();
+	bootscreeninit();
 	if(i8237alloc != nil)
 		i8237alloc();
 	trapinit();

sys/src/9/pc64/memory.c

@@ -371,6 +371,34 @@ sigsearch(char* signature)
 	return sigscan(KADDR(0xe0000), 0x20000, signature);
 }
 
+static void
+lowraminit(void)
+{
+	uintptr pa, x;
+	uchar *bda;
+
+	/*
+	 * Initialise the memory bank information for conventional memory
+	 * (i.e. less than 640KB). The base is the first location after the
+	 * bootstrap processor MMU information and the limit is obtained from
+	 * the BIOS data area.
+	 */
+	x = PADDR(CPU0END);
+	bda = (uchar*)KADDR(0x400);
+	pa = ((bda[0x14]<<8)|bda[0x13])*KB;
+	if(x < pa){
+		mapfree(&rmapram, x, pa-x);
+		memset(KADDR(x), 0, pa-x);		/* keep us honest */
+	}
+
+	x = PADDR(PGROUND((uintptr)end));
+	pa = MemMin;
+	if(x > pa)
+		panic("kernel too big");
+	mapfree(&rmapram, x, pa-x);
+	memset(KADDR(x), 0, pa-x);		/* keep us honest */
+}
+
 typedef struct Emap Emap;
 struct Emap
 {
@@ -561,6 +589,7 @@ meminit(void)
 	uintptr lost;
 
 	umbscan();
+	lowraminit();
 	e820scan();
 
 	/*

sys/src/9/pc64/mmu.c

@@ -23,8 +23,6 @@ Segdesc gdt[NGDT] =
 [UESEG]		EXECSEGM(3),		/* user code */
 };
 
-static int didmmuinit = 0;
-
 static struct {
 	Lock;
 	MMU	*free;
@@ -79,8 +77,6 @@ mmuinit(void)
 	vlong v;
 	int i;
 
-	didmmuinit = 1;
-
 	/* zap double map done by l.s */ 
 	m->pml4[512] = 0;
 	m->pml4[0] = 0;
@@ -242,7 +238,7 @@ mmucreate(uintptr *table, uintptr va, int level, int index)
 			up->kmapcount++;
 		}
 		page = p->page;
-	} else if(didmmuinit) {
+	} else if(conf.mem[0].npage != 0) {
 		page = mallocalign(PTSZ, BY2PG, 0, 0);
 	} else {
 		page = rampage();