initial support for pflash / cbfs
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/Makefile b/Makefile
index 6db2104..bcefa27 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
obj-y = code16.o entry.o main.o string.o printf.o cstart.o fw_cfg.o
-obj-y += linuxboot.o malloc.o
+obj-y += linuxboot.o malloc.o pflash.o
all-y = bios.bin
all: $(all-y)
diff --git a/include/pflash.h b/include/pflash.h
new file mode 100644
index 0000000..1dbbeae
--- /dev/null
+++ b/include/pflash.h
@@ -0,0 +1,8 @@
+#ifndef BIOS_PFLASH_H
+#define BIOS_PFLASH_H 1
+
+#include <stdint.h>
+
+void *pflash_base(int n, size_t *size);
+
+#endif
diff --git a/main.c b/main.c
index 74c4057..033ea2f 100644
--- a/main.c
+++ b/main.c
@@ -1,3 +1,4 @@
+#include <stdbool.h>
#include "bios.h"
#include "stdio.h"
#include "e820.h"
@@ -5,6 +6,7 @@
#include "string.h"
#include "segment.h"
#include "fw_cfg.h"
+#include "pflash.h"
#define PCI_VENDOR_ID_INTEL 0x8086
#define PCI_DEVICE_ID_INTEL_82441 0x1237
@@ -15,6 +17,9 @@
static void make_bios_writable(void)
{
+ // NOTE: this runs from ROM at 0xFFFF0000, so it is not possible to use any
+ // static data.
+
const int bdf = 0;
const uint8_t *bios_start = (uint8_t *)0xffff0000;
uint8_t *low_start = (uint8_t *)0xf0000;
@@ -39,6 +44,10 @@
// We're still running from 0xffff0000
pci_config_writeb(bdf, pambase, 0x30);
memcpy(low_start, bios_start, 0x10000);
+
+ // Now go to the F-segment: we need to move away from flash area
+ // in order to probe CBFS!
+ asm("ljmp $0x8, $1f; 1:");
}
static void set_realmode_int(int vec, void *p)
@@ -111,6 +120,18 @@
e820_seg = ((uintptr_t) e820) >> 4;
}
+static bool detect_cbfs_and_boot(void)
+{
+ size_t sz;
+ void *base = pflash_base(1, &sz);
+
+ if (!base)
+ return false;
+
+ // return boot_from_cbfs(base, sz);
+ return false;
+}
+
int main(void)
{
make_bios_writable();
@@ -122,6 +143,7 @@
// extract_smbios();
// extract_kernel();
// make_bios_readonly();
- boot_from_fwcfg();
+ if (!detect_cbfs_and_boot())
+ boot_from_fwcfg();
panic();
}
diff --git a/pflash.c b/pflash.c
new file mode 100644
index 0000000..950bc74
--- /dev/null
+++ b/pflash.c
@@ -0,0 +1,63 @@
+#include <stddef.h>
+#include "bios.h"
+#include "pflash.h"
+#include "stdio.h"
+
+#define CLEAR_STATUS_CMD 0x50
+#define READ_STATUS_CMD 0x70
+#define QUERY_CMD 0x98
+#define READ_ARRAY_CMD 0xff
+
+static void *pflash_detect(uint8_t *top_addr)
+{
+ volatile uint8_t *p = top_addr;
+ uint8_t save;
+ int i, blocks, sector_len;
+
+ /* The low byte of the address is part of the command, so it must be 0. */
+ if ((uintptr_t)p & 256)
+ panic();
+
+ p -= 256;
+ for (i = 0; i < 256; i++)
+ if (p[i] != CLEAR_STATUS_CMD)
+ break;
+ if (i == 256)
+ return NULL;
+
+ save = p[i];
+ p[i] = CLEAR_STATUS_CMD;
+ if (p[i] == CLEAR_STATUS_CMD) {
+ /* behaves as RAM */
+ p[i] = save;
+ return NULL;
+ }
+ p[i] = READ_STATUS_CMD;
+ if (p[i] != 0) {
+ /* doesn't behave as flash */
+ return NULL;
+ }
+
+ /* 0x2d-0x2e: blocks_per_device - 1, little endian */
+ /* 0x2f-0x30: sector_len / 256 */
+ p[i] = QUERY_CMD;
+ blocks = p[0x2d] + (p[0x2e] << 8) + 1;
+ sector_len = (p[0x2f] + (p[0x30] << 8)) << 8;
+
+ p[i] = READ_ARRAY_CMD;
+ return top_addr - blocks * sector_len;
+}
+
+void *pflash_base(int n, size_t *size)
+{
+ uint8_t *top = NULL;
+ uint8_t *prev;
+ while (n-- >= 0) {
+ prev = top;
+ top = pflash_detect(top);
+ if (!top)
+ return NULL;
+ *size = prev - top;
+ }
+ return top;
+}
