Place multiboot command lines in base memory; Xen won't pick them up

otherwise.  :(

diff --git a/src/arch/i386/image/multiboot.c b/src/arch/i386/image/multiboot.c
index dfd872c..fbaebd5 100644 (file)
--- a/src/arch/i386/image/multiboot.c
+++ b/src/arch/i386/image/multiboot.c
@@ -23,6 +23,7 @@
  *
  */
 
+#include <stdio.h>
 #include <errno.h>
 #include <assert.h>
 #include <realmode.h>
@@ -51,6 +52,16 @@ struct image_type multiboot_image_type __image_type ( PROBE_MULTIBOOT );
  */
 #define MAX_MODULES 8
 
+/**
+ * Maximum combined length of command lines
+ *
+ * Again; sorry.  Some broken OSes zero out any non-base memory that
+ * isn't part of the loaded module set, so we can't just use
+ * virt_to_phys(cmdline) to point to the command lines, even though
+ * this would comply with the Multiboot spec.
+ */
+#define MB_MAX_CMDLINE 512
+
 /** Multiboot flags that we support */
 #define MB_SUPPORTED_FLAGS ( MB_FLAG_PGALIGN | MB_FLAG_MEMMAP | \
                             MB_FLAG_VIDMODE | MB_FLAG_RAW )
@@ -77,6 +88,13 @@ struct multiboot_header_info {
        size_t offset;
 };
 
+/** Multiboot module command lines */
+static char __bss16_array ( mb_cmdlines, [MB_MAX_CMDLINE] );
+#define mb_cmdlines __use_data16 ( mb_cmdlines )
+
+/** Offset within module command lines */
+static unsigned int mb_cmdline_offset;
+
 /**
  * Build multiboot memory map
  *
@@ -118,6 +136,32 @@ static void multiboot_build_memmap ( struct image *image,
        }
 }
 
+/**
+ * Add command line in base memory
+ *
+ * @v cmdline          Command line
+ * @ret physaddr       Physical address of command line
+ */
+physaddr_t multiboot_add_cmdline ( const char *cmdline ) {
+       char *mb_cmdline;
+
+       if ( ! cmdline )
+               cmdline = "";
+
+       /* Copy command line to base memory buffer */
+       mb_cmdline = ( mb_cmdlines + mb_cmdline_offset );
+       mb_cmdline_offset +=
+               ( snprintf ( mb_cmdline,
+                            ( sizeof ( mb_cmdlines ) - mb_cmdline_offset ),
+                            "%s", cmdline ) + 1 );
+
+       /* Truncate to terminating NUL in buffer if necessary */
+       if ( mb_cmdline_offset > sizeof ( mb_cmdlines ) )
+               mb_cmdline_offset = ( sizeof ( mb_cmdlines ) - 1 );
+
+       return virt_to_phys ( mb_cmdline );
+}
+
 /**
  * Build multiboot module list
  *
@@ -135,7 +179,6 @@ multiboot_build_module_list ( struct image *image,
        unsigned int insert;
        physaddr_t start;
        physaddr_t end;
-       char *cmdline;
        unsigned int i;
 
        /* Add each image as a multiboot module */
@@ -151,44 +194,35 @@ multiboot_build_module_list ( struct image *image,
                if ( module_image == image )
                        continue;
 
-               /* If we don't have a data structure to populate, just count */
-               if ( modules ) {
-                       
-                       /* At least some OSes expect the multiboot
-                        * modules to be in ascending order, so we
-                        * have to support it.
-                        */
-                       start = user_to_phys ( module_image->data, 0 );
-                       end = user_to_phys ( module_image->data,
-                                            module_image->len );
-                       for ( insert = 0 ; insert < count ; insert++ ) {
-                               if ( start < modules[insert].mod_start )
-                                       break;
-                       }
-                       module = &modules[insert];
-                       memmove ( ( module + 1 ), module,
-                                 ( ( count - insert ) * sizeof ( *module ) ));
-                       module->mod_start = start;
-                       module->mod_end = end;
-                       cmdline = ( module_image->cmdline ?
-                                   module_image->cmdline : "" );
-                       module->string = virt_to_phys ( cmdline );
-                       module->reserved = 0;
-                       
-                       /* We promise to page-align modules */
-                       assert ( ( module->mod_start & 0xfff ) == 0 );
+               /* At least some OSes expect the multiboot modules to
+                * be in ascending order, so we have to support it.
+                */
+               start = user_to_phys ( module_image->data, 0 );
+               end = user_to_phys ( module_image->data, module_image->len );
+               for ( insert = 0 ; insert < count ; insert++ ) {
+                       if ( start < modules[insert].mod_start )
+                               break;
                }
+               module = &modules[insert];
+               memmove ( ( module + 1 ), module,
+                         ( ( count - insert ) * sizeof ( *module ) ) );
+               module->mod_start = start;
+               module->mod_end = end;
+               module->string =
+                       multiboot_add_cmdline ( module_image->cmdline );
+               module->reserved = 0;
+               
+               /* We promise to page-align modules */
+               assert ( ( module->mod_start & 0xfff ) == 0 );
 
                count++;
        }
 
        /* Dump module configuration */
-       if ( modules ) {
-               for ( i = 0 ; i < count ; i++ ) {
-                       DBGC ( image, "MULTIBOOT %p module %d is [%lx,%lx)\n",
-                              image, i, modules[i].mod_start,
-                              modules[i].mod_end );
-               }
+       for ( i = 0 ; i < count ; i++ ) {
+               DBGC ( image, "MULTIBOOT %p module %d is [%lx,%lx)\n",
+                      image, i, modules[i].mod_start,
+                      modules[i].mod_end );
        }
 
        return count;
@@ -225,7 +259,6 @@ static struct multiboot_module __bss16_array ( mbmodules, [MAX_MODULES] );
  */
 static int multiboot_exec ( struct image *image ) {
        physaddr_t entry = image->priv.phys;
-       char *cmdline;
 
        /* Populate multiboot information structure */
        memset ( &mbinfo, 0, sizeof ( mbinfo ) );
@@ -233,8 +266,8 @@ static int multiboot_exec ( struct image *image ) {
                         MBI_FLAG_CMDLINE | MBI_FLAG_MODS );
        multiboot_build_memmap ( image, &mbinfo, mbmemmap,
                                 ( sizeof(mbmemmap) / sizeof(mbmemmap[0]) ) );
-       cmdline = ( image->cmdline ? image->cmdline : "" );
-       mbinfo.cmdline = virt_to_phys ( cmdline );
+       mb_cmdline_offset = 0;
+       mbinfo.cmdline = multiboot_add_cmdline ( image->cmdline );
        mbinfo.mods_count = multiboot_build_module_list ( image, mbmodules,
                                ( sizeof(mbmodules) / sizeof(mbmodules[0]) ) );
        mbinfo.mods_addr = virt_to_phys ( mbmodules );