domain builder: multiboot-like module support

This defines how multiple modules can be passed to a domain by packing
them together into a "multiboot module" in a way very similar to the
multiboot standard.  An SIF_ flag is added to announce such package.
This also adds a packing implementation to PV-GRUB.

Signed-Off-By: Samuel Thibault <samuel.thibault@ens-lyon.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
index 50692a03a4..d46b1dd37e 100644
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -584,8 +584,35 @@ typedef struct start_info start_info_t;
 /* These flags are passed in the 'flags' field of start_info_t. */
 #define SIF_PRIVILEGED    (1<<0)  /* Is the domain privileged? */
 #define SIF_INITDOMAIN    (1<<1)  /* Is this the initial control domain? */
+#define SIF_MULTIBOOT_MOD (1<<2)  /* Is mod_start a multiboot module? */
 #define SIF_PM_MASK       (0xFF<<8) /* reserve 1 byte for xen-pm options */
 
+/*
+ * A multiboot module is a package containing modules very similar to a
+ * multiboot module array. The only differences are:
+ * - the array of module descriptors is by convention simply at the beginning
+ *   of the multiboot module,
+ * - addresses in the module descriptors are based on the beginning of the
+ *   multiboot module,
+ * - the number of modules is determined by a termination descriptor that has
+ *   mod_start == 0.
+ *
+ * This permits to both build it statically and reference it in a configuration
+ * file, and let the PV guest easily rebase the addresses to virtual addresses
+ * and at the same time count the number of modules.
+ */
+struct xen_multiboot_mod_list
+{
+    /* Address of first byte of the module */
+    uint32_t mod_start;
+    /* Address of last byte of the module (inclusive) */
+    uint32_t mod_end;
+    /* Address of zero-terminated command line */
+    uint32_t cmdline;
+    /* Unused, must be zero */
+    uint32_t pad;
+};
+
 typedef struct dom0_vga_console_info {
     uint8_t video_type; /* DOM0_VGA_CONSOLE_??? */
 #define XEN_VGATYPE_TEXT_MODE_3 0x03