Re: [Qemu-devel] [PATCH v2 1/6] Use IO port for qemu<->guest BIOS communication.

[Gleb Natapov <gleb@qumranet.com>]

On Mon, Aug 25, 2008 at 09:27:18PM +0300, Blue Swirl wrote:
> >  Blue Swirl: What do you think of switching sparc to use a structure more
> > like this?  I do prefer a key-value mechanism verses a blob.  Even with pure
> > MMIO, the same results could be achieved by treating the MMIO region as
> > registers and using a selector.
> 
> I could switch Sparc to something like this, if the goal is that it
> will be used by all targets.
> 
> There should be a .h file which lists the keys and which can be
> included from C and asm, like current firmware_abi.h. I'd define an
> offset (0x8000?) for architecture-specific keys which need not be in
> the same .h file.

Is the patch below what you mean? (not tested, but compiles)


---

    Use IO port for qemu<->guest BIOS communication.
    
    Use PIO to get configuration info between qemu process and guest BIOS.
    
    Signed-off-by: Gleb Natapov <gleb@qumranet.com>

diff --git a/hw/fw_channel.h b/hw/fw_channel.h
new file mode 100644
index 0000000..3d44af1
--- /dev/null
+++ b/hw/fw_channel.h
@@ -0,0 +1,68 @@
+#ifndef FW_CHANNEL_H
+#define FW_CHANNEL_H
+
+#define FW_CFG_SIGNATURE        0x00
+#define FW_CFG_ID               0x01
+#define FW_CFG_MAX_ENTRY        0x10
+
+#define FW_CFG_ARCH_LOCAL       0x8000
+
+#ifndef __ASSEMBLY__
+
+typedef struct _FWCfgEntry {
+    uint16_t len;
+    uint8_t *data;
+} FWCfgEntry;
+
+typedef struct _FWCfgState {
+    FWCfgEntry entries[2][FW_CFG_MAX_ENTRY];
+    FWCfgEntry *cur_entry;
+    uint16_t cur_offset;
+} FWCfgState;
+
+static inline int firmware_cfg_add(FWCfgState *s, uint16_t key,
+        uint8_t *data, uint16_t len)
+{
+    int arch = key & FW_CFG_ARCH_LOCAL;
+
+    key &= (~FW_CFG_ARCH_LOCAL);
+
+    if (key >= FW_CFG_MAX_ENTRY)
+        return 0;
+
+    s->entries[arch][key].data = data;
+    s->entries[arch][key].len = len;
+
+    return 1;
+}
+
+static inline int firmware_cfg_select(FWCfgState *s, uint16_t key)
+{
+    int arch = key & FW_CFG_ARCH_LOCAL;
+
+    key &= (~FW_CFG_ARCH_LOCAL);
+
+    s->cur_offset = 0;
+    if (key >= FW_CFG_MAX_ENTRY) {
+        s->cur_entry = NULL;
+        return 0;
+    }
+
+    s->cur_entry = &s->entries[arch][key];
+
+    return 1;
+}
+
+static inline uint8_t firmware_cfg_read(FWCfgState *s)
+{
+    FWCfgEntry *e = s->cur_entry;
+
+    if (!e || !e->data || s->cur_offset >= e->len)
+        return 0;
+
+    return e->data[s->cur_offset++];
+}
+
+#endif /* __ASSEMBLY__ */
+
+#endif
diff --git a/hw/pc.c b/hw/pc.c
index 213ead8..db5089b 100644
--- a/hw/pc.c
+++ b/hw/pc.c
@@ -32,6 +32,7 @@
 #include "smbus.h"
 #include "boards.h"
 #include "console.h"
+#include "hw/fw_channel.h"
 
 /* output Bochs bios info messages */
 //#define DEBUG_BIOS
@@ -44,6 +45,7 @@
 
 /* Leave a chunk of memory at the top of RAM for the BIOS ACPI tables.  */
 #define ACPI_DATA_SIZE       0x10000
+#define BIOS_CFG_IOPORT 0x510
 
 #define MAX_IDE_BUS 2
 
@@ -53,6 +55,9 @@ static PITState *pit;
 static IOAPICState *ioapic;
 static PCIDevice *i440fx_state;
 
+static uint32_t bios_cfg_id = 1;
+static FWCfgState *bios_params;
+
 static void ioport80_write(void *opaque, uint32_t addr, uint32_t data)
 {
 }
@@ -367,6 +372,21 @@ static uint32_t ioport92_read(void *opaque, uint32_t addr)
     return ioport_get_a20() << 1;
 }
 
+static uint32_t bios_cfg_read(void *opaque, uint32_t addr)
+{
+    FWCfgState *s = opaque;
+
+    return firmware_cfg_read(s);
+}
+
+static void bios_cfg_write(void *opaque, uint32_t addr, uint32_t value)
+{
+    FWCfgState *s = opaque;
+
+    firmware_cfg_select(s, (uint16_t)value);
+}
+
+
 /***********************************************************/
 /* Bochs BIOS debug ports */
 
@@ -426,6 +446,14 @@ static void bochs_bios_init(void)
     register_ioport_write(0x502, 1, 2, bochs_bios_write, NULL);
     register_ioport_write(0x500, 1, 1, bochs_bios_write, NULL);
     register_ioport_write(0x503, 1, 1, bochs_bios_write, NULL);
+
+    bios_params = qemu_mallocz(sizeof(FWCfgState));
+
+    register_ioport_read(BIOS_CFG_IOPORT, 1, 1, bios_cfg_read, bios_params);
+    register_ioport_write(BIOS_CFG_IOPORT, 1, 1, bios_cfg_write, bios_params);
+
+    firmware_cfg_add(bios_params, FW_CFG_SIGNATURE, "QEMU", 4);
+    firmware_cfg_add(bios_params, FW_CFG_ID, (uint8_t*)&bios_cfg_id, 4);
 }
 
 /* Generate an initial boot sector which sets state and jump to
--
			Gleb.