[Xen-devel] [PATCH] Magic header in start_info page

[Rusty Russell <rusty@xxxxxxxxxxxxxxx>]

To allow kernel to handle radically different hypervisors in the future,
I thought a magic field in the start_info might be useful.  I just chose
"Xen-<major>.<minor>", but feel free to change it.

Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx> (authored)

diff -r 94cee9a918de tools/libxc/xc_linux_build.c
--- a/tools/libxc/xc_linux_build.c      Sat Oct 22 07:35:03 2005
+++ b/tools/libxc/xc_linux_build.c      Mon Oct 24 17:23:24 2005
@@ -350,6 +350,8 @@
     start_info = xc_map_foreign_range(
         xc_handle, dom, PAGE_SIZE, PROT_READ|PROT_WRITE, page_array[0]);
     memset(start_info, 0, sizeof(*start_info));
+    rc = xc_version(xc_handle, XENVER_version, NULL);
+    sprintf(start_info->magic, "Xen-%i.%i", rc >> 16, rc & (0xFFFF));
     start_info->flags        = flags;
     start_info->store_mfn    = nr_pages - 2;
     start_info->store_evtchn = store_evtchn;
@@ -624,6 +626,8 @@
         xc_handle, dom, PAGE_SIZE, PROT_READ|PROT_WRITE,
         page_array[(vstartinfo_start-dsi.v_start)>>PAGE_SHIFT]);
     memset(start_info, 0, sizeof(*start_info));
+    rc = xc_version(xc_handle, XENVER_version, NULL);
+    sprintf(start_info->magic, "Xen-%i.%i", rc >> 16, rc & (0xFFFF));
     start_info->nr_pages     = nr_pages;
     start_info->shared_info  = shared_info_frame << PAGE_SHIFT;
     start_info->flags        = flags;
diff -r 94cee9a918de xen/arch/ia64/xen/domain.c
--- a/xen/arch/ia64/xen/domain.c        Sat Oct 22 07:35:03 2005
+++ b/xen/arch/ia64/xen/domain.c        Mon Oct 24 17:23:24 2005
@@ -28,6 +28,7 @@
 #include <xen/event.h>
 //#include <xen/shadow.h>
 #include <xen/console.h>
+#include <xen/compile.h>
 
 #include <xen/elf.h>
 //#include <asm/page.h>
@@ -930,6 +931,7 @@
        si = (start_info_t *)alloc_xenheap_page();
        memset(si, 0, PAGE_SIZE);
        d->shared_info->arch.start_info_pfn = __pa(si) >> PAGE_SHIFT;
+       sprintf(si->magic, "Xen-%i.%i", XEN_VERSION, XEN_SUBVERSION);
 
 #if 0
        si->nr_pages     = d->tot_pages;
diff -r 94cee9a918de xen/arch/x86/domain_build.c
--- a/xen/arch/x86/domain_build.c       Sat Oct 22 07:35:03 2005
+++ b/xen/arch/x86/domain_build.c       Mon Oct 24 17:23:24 2005
@@ -15,6 +15,7 @@
 #include <xen/elf.h>
 #include <xen/kernel.h>
 #include <xen/domain.h>
+#include <xen/compile.h>
 #include <asm/regs.h>
 #include <asm/system.h>
 #include <asm/io.h>
@@ -602,6 +603,7 @@
     si->pt_base      = vpt_start;
     si->nr_pt_frames = nr_pt_pages;
     si->mfn_list     = vphysmap_start;
+    sprintf(si->magic, "Xen-%i.%i", XEN_VERSION, XEN_SUBVERSION);
 
     /* Write the phys->machine and machine->phys table entries. */
     for ( pfn = 0; pfn < d->tot_pages; pfn++ )
diff -r 94cee9a918de xen/include/public/xen.h
--- a/xen/include/public/xen.h  Sat Oct 22 07:35:03 2005
+++ b/xen/include/public/xen.h  Mon Oct 24 17:23:24 2005
@@ -410,6 +410,7 @@
 #define MAX_GUEST_CMDLINE 1024
 typedef struct start_info {
     /* THE FOLLOWING ARE FILLED IN BOTH ON INITIAL BOOT AND ON RESUME.    */
+    char magic[32];             /* "Xen-<version>.<subversion>". */
     unsigned long nr_pages;     /* Total pages allocated to this domain.  */
     unsigned long shared_info;  /* MACHINE address of shared info struct. */
     uint32_t flags;             /* SIF_xxx flags.                         */

-- 
A bad analogy is like a leaky screwdriver -- Richard Braakman


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