skip PAM if unnecessary
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/hwsetup.c b/hwsetup.c
index 2924383..0e186eb 100644
--- a/hwsetup.c
+++ b/hwsetup.c
@@ -82,11 +82,25 @@
outb(0x4d1, 0x0c);
}
+void setup_pam(int bdf, int pambase)
+{
+ int i;
+ for (i=0; i<6; i++) {
+ int pam = pambase + 1 + i;
+ pci_config_writeb(bdf, pam, 0x33);
+ }
+
+ // Make ram from 0xf0000-0x100000 read-write
+ pci_config_writeb(bdf, pambase, 0x30);
+}
+
void setup_hw(void)
{
const int bdf = 0;
const uint8_t *bios_start = &stext + 0xfff00000;
const uint8_t *init_start = &sinit + 0xfff00000;
+ volatile uint8_t *rom_check = &stext;
+ int rom_check_value;
int pambase;
uint32_t id = pci_config_readl(bdf, 0);
@@ -102,15 +116,12 @@
panic();
// Make ram from 0xc0000-0xf0000 read-write
- int i;
- for (i=0; i<6; i++) {
- int pam = pambase + 1 + i;
- pci_config_writeb(bdf, pam, 0x33);
- }
+ rom_check_value = *rom_check;
+ *rom_check = rom_check_value + 1;
+ if (*rom_check == rom_check_value)
+ setup_pam(bdf, pambase);
- // Make ram from 0xf0000-0x100000 read-write and shadow BIOS
- // We're still running from 0xffff0000
- pci_config_writeb(bdf, pambase, 0x30);
+ // Shadow BIOS; we're still running from 0xffff0000
memcpy(&stext, bios_start, &edata - &stext);
memcpy(&sinit, init_start, &einit - &sinit);
