[SeaBIOS] [PATCH v2 4/5] acpi: load and link tables from /etc/acpi/

[Michael S. Tsirkin]

Load files in /etc/acpi/, link them using
a linker script and use for acpi tables, including the RSDP.
Presense of RSDP in this directory completely disables
generating and loading legacy acpi tables.

Signed-off-by: Michael S. Tsirkin 
---
 src/acpi.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/src/acpi.c b/src/acpi.c
index a81f0cb..07d311a 100644
--- a/src/acpi.c
+++ b/src/acpi.c
@@ -27,6 +27,7 @@
 #include "config.h" // CONFIG_*
 #include "paravirt.h" // RamSize
 #include "dev-q35.h"
+#include "linker.h"

#include "acpi-dsdt.hex"

@@ -599,6 +600,34 @@ static const struct pci_device_id acpi_find_tbl[] = {

struct rsdp_descriptor *RsdpAddr;

+/* Look for RSDP signature in files loaded in FSEG */
+struct rsdp_descriptor *
+acpi_find_rsdp_rom(void)
+{
+    struct romfile_s *file = NULL;
+    struct rsdp_descriptor *rsdp = NULL;
+    for (;;) {
+        file = romfile_findprefix("", file);
+        if (!file)
+            break;
+
+        if (!file->data || !pmm_test_fseg(file->data) ||
+            file->size < sizeof(rsdp->signature))
+            continue;
+
+        void *data;
+
+        for (data = file->data;
+             data + sizeof(*rsdp) <= file->data + file->size;
+             data++) {
+            rsdp = data;
+            if (rsdp->signature == cpu_to_le64(RSDP_SIGNATURE))
+                return rsdp;
+        }
+    }
+    return NULL;
+}
+
 #define MAX_ACPI_TABLES 20
 void
 acpi_setup(void)
@@ -608,6 +637,16 @@ acpi_setup(void)

dprintf(3, "init ACPI tables\n");

+    linker_loader_execute("/etc/linker-script");
+
+    RsdpAddr = acpi_find_rsdp_rom();
+
+    if (RsdpAddr) {
+        return;
+    }
+
+    dprintf(3, "generate ACPI tables\n");
+
     // This code is hardcoded for PIIX4 Power Management device.
     struct pci_device *pci = pci_find_init_device(acpi_find_tbl, NULL);
     if (!pci)