./sign.pl bootblock
bootother: bootother.S
- $(CC) $(CFLAGS) -nostdinc -I. -c bootother.S
- $(LD) $(LDFLAGS) -N -e start -Ttext 0x7000 -o bootother.out bootother.o
- $(OBJCOPY) -S -O binary bootother.out bootother
- $(OBJDUMP) -S bootother.o > bootother.asm
+ $(CC) $(CFLAGS) -fno-pic -nostdinc -I. -c bootother.S
+ $(LD) $(LDFLAGS) -N -e start -Ttext 0x7000 -o bootblockother.o bootother.o
+ $(OBJCOPY) -S -O binary -j .text bootblockother.o bootother
+ $(OBJDUMP) -S bootblockother.o > bootother.asm
initcode: initcode.S
$(CC) $(CFLAGS) -nostdinc -I. -c initcode.S
then echo "-gdb tcp::$(GDBPORT)"; \
else echo "-s -p $(GDBPORT)"; fi)
ifndef CPUS
-CPUS := 1
+CPUS := 2
endif
QEMUOPTS = -hdb fs.img xv6.img -smp $(CPUS) -m 512
# Bootothers (in main.c) sends the STARTUPs one at a time.
# It copies this code (start) at 0x7000.
# It puts the address of a newly allocated per-core stack in start-4,
-# and the address of the place to jump to (mpmain) in start-8.
+# the address of the place to jump to (mpboot) in start-8, and the physical
+# address of bootpgdir in start-12.
+#
#
# This code is identical to bootasm.S except:
# - it does not need to enable A20
-# - it uses the address at start-4 for the %esp
-# - it jumps to the address at start-8 instead of calling bootmain
+# - it uses the address at start-4, start-8, and start-12
.code16
.globl start
movl %eax, %cr0
//PAGEBREAK!
- ljmpl $(SEG_KCODE<<3), $(start32+KERNBASE)
+ ljmpl $(SEG_KCODE<<3), $(start32)
.code32
start32:
movw %ax, %fs
movw %ax, %gs
- # switch to the stack allocated by bootothers()
- movl P2V_WO(start-4), %esp
+ # Use bootpgdir as our initial page table
+ movl (start-12), %eax
+ movl %eax, %cr3
+ # Turn on paging.
+ movl %cr0, %eax
+ orl $(CR0_PE|CR0_PG|CR0_WP), %eax
+ movl %eax, %cr0
- # call mpmain()
- call *(P2V_WO(start)-8)
+ # Switch to the stack allocated by bootothers()
+ movl (start-4), %esp
+ # Call mpboot()
+ call *(start-8)
movw $0x8a00, %ax
movw %ax, %dx
.p2align 2
gdt:
SEG_NULLASM
- SEG_ASM(STA_X|STA_R, -KERNBASE, 0xffffffff)
- SEG_ASM(STA_W, -KERNBASE, 0xffffffff)
+ SEG_ASM(STA_X|STA_R, 0, 0xffffffff)
+ SEG_ASM(STA_W, 0, 0xffffffff)
gdtdesc:
.word (gdtdesc - gdt - 1)
.long gdt
+
void
lapicinit(int c)
{
- cprintf("lapicinit: %d 0x%x\n", c, lapic);
if(!lapic)
return;
static void bootothers(void);
static void mpmain(void) __attribute__((noreturn));
-static volatile int newpgdir;
+extern pde_t *kpgdir;
// Bootstrap processor starts running C code here.
// Allocate a real stack and switch to it, first
lapicinit(mpbcpu());
seginit(); // set up segments
cprintf("\ncpu%d: starting xv6\n\n", cpu->id);
- kinit(); // initialize memory allocator
picinit(); // interrupt controller
ioapicinit(); // another interrupt controller
consoleinit(); // I/O devices & their interrupts
ideinit(); // disk
if(!ismp)
timerinit(); // uniprocessor timer
- userinit(); // first user process
- bootothers(); // start other processors
- newpgdir = 1;
+ bootothers(); // start other processors (must come before kinit; must use boot_alloc)
+ kinit(); // initialize memory allocator
+ userinit(); // first user process (must come after kinit)
// Finish setting up this processor in mpmain.
mpmain();
}
-// Common CPU setup code.
-// Bootstrap CPU comes here from mainc().
// Other CPUs jump here from bootother.S.
static void
mpboot(void)
{
- vmenable(); // turn on paging
+ switchkvm();
seginit();
lapicinit(cpunum());
mpmain();
}
// Common CPU setup code.
-// Bootstrap CPU comes here from mainc().
-// Other CPUs jump here from bootother.S.
static void
mpmain(void)
{
cprintf("cpu%d: starting\n", cpu->id);
idtinit(); // load idt register
xchg(&cpu->booted, 1); // tell bootothers() we're up
- while (!newpgdir) ; // wait until we have new page dir
- switchkvm(); // switch to new page dir
scheduler(); // start running processes
}
+pde_t bootpgdir[];
+
// Start the non-boot processors.
static void
bootothers(void)
if(c == cpus+cpunum()) // We've started already.
continue;
- // Tell bootother.S what stack to use and the address of mpmain;
- // it expects to find these two addresses stored just before
- // its first instruction.
- stack = kalloc();
+ // Tell bootother.S what stack to use, the address of mpboot and pgdir;
+ stack = boot_alloc(); // We need a stack below 4Mbyte with bootpgdir
*(void**)(code-4) = stack + KSTACKSIZE;
*(void**)(code-8) = mpboot;
+ *(int**)(code-12) = (void *) v2p(bootpgdir);
lapicstartap(c->id, v2p(code));
- // Wait for cpu to finish mpmain()
+ // wait for cpu to finish mpmain()
while(c->booted == 0)
;
}
}
-// Boot page table used in multiboot.S.
+// Boot page table used in multiboot.S and bootother.S.
// Page directories (and page tables), must start on a page boundary,
// hence the "__aligned__" attribute. Also, because of restrictions
// related to linking and static initializers, we use "x + PTE_P"
// here, rather than the more standard "x | PTE_P". Everywhere else
// you should use "|" to combine flags.
-pte_t entry_pgtable[NPTENTRIES];
pte_t dev_pgtable[NPTENTRIES];
+pte_t entry_pgtable[NPTENTRIES];
__attribute__((__aligned__(PGSIZE)))
pde_t bootpgdir[NPDENTRIES] = {
// Map VA's [0, 4MB) to PA's [0, 4MB)
[0]
- = ((uint)entry_pgtable - KERNBASE) + PTE_P,
+ = ((uint)entry_pgtable - KERNBASE) + PTE_P + PTE_W,
// Map VA's [KERNBASE, KERNBASE+4MB) to PA's [0, 4MB)
[KERNBASE>>PDXSHIFT]
= ((uint)entry_pgtable - KERNBASE) + PTE_P + PTE_W,
- // Map VA's [DEVSPACE, DEVSPACE+4MB) to PA's [DEVSPACE, 4MB)
- [0xFEE00000>>PDXSHIFT]
- = ((uint)dev_pgtable - KERNBASE) + PTE_P + PTE_W,
};
// XXX switch to super pages
#include "elf.h"
extern char data[]; // defined in data.S
-static pde_t *kpgdir; // for use in scheduler()
+pde_t *kpgdir; // for use in scheduler()
struct segdesc gdt[NSEGS];
// Set up CPU's kernel segment descriptors.
}
// Return the address of the PTE in page table pgdir
-// that corresponds to linear address va. If create!=0,
+// that corresponds to linear address va. If alloc!=0,
// create any required page table pages.
static pte_t *
walkpgdir(pde_t *pgdir, const void *va, char* (*alloc)(void))
// setupkvm() and exec() set up every page table like this:
// 0..USERTOP : user memory (text, data, stack, heap), mapped to some unused phys mem
// KERNBASE..KERNBASE+1M: mapped to 0..1M
-// KERNBASE+1M..KERNBASE+end : mapped to 1M..end
-// KERNBASE+end..KERBASE+PHYSTOP : mapped to end..PHYSTOP (free memory)
+// KERNBASE+1M..KERNBASE+end : mapped to 1M..end (mapped without write permission)
+// KERNBASE+end..KERBASE+PHYSTOP : mapped to end..PHYSTOP (rw data + free memory)
// 0xfe000000..0 : mapped direct (devices such as ioapic)
//
// The kernel allocates memory for its heap and for user memory
switchkvm();
}
-// Turn on paging.
-void
-vmenable(void)
-{
- uint cr0;
-
- switchkvm(); // load kpgdir into cr3
- cr0 = rcr0();
- cr0 |= CR0_PG;
- lcr0(cr0);
-
- struct cpu *c = &cpus[0];
- lgdt((void *)v2p((void *)(c->gdt)), sizeof(c->gdt));
- loadgs(SEG_KCPU << 3);
- loadfs(SEG_KDATA << 3);
- loades(SEG_KDATA << 3);
- loadds(SEG_KDATA << 3);
- loadss(SEG_KDATA << 3);
-
- __asm volatile("ljmp %0,$1f\n 1:\n" :: "i" (SEG_KCODE << 3)); // reload cs
-}
-
// Switch h/w page table register to the kernel-only page table,
// for when no process is running.
void
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