memdisk: add a sector_shift field to the MDI; fix memdiskfind

Add a sector_shift field to the MDI rather than assuming 512-byte
sectors.  Fix memdiskfind to report size in bytes, not in sectors.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

2 files changed, 12 insertions, 11 deletions

diff --git a/memdisk/mstructs.h b/memdisk/mstructs.h
index c2e6352b..fecbff40 100644
--- a/memdisk/mstructs.h
+++ b/memdisk/mstructs.h
@@ -93,7 +93,7 @@ struct mdi {
 
     uint16_t olddosmem;
     uint8_t bootloaderid;
-    uint8_t _pad1;
+    uint8_t sector_shift;
 
     uint16_t dpt_ptr;
 } MEMDISK_PACKED_POSTFIX;
diff --git a/memdisk/setup.c b/memdisk/setup.c
index 20b48c47..3f69cd35 100644
--- a/memdisk/setup.c
+++ b/memdisk/setup.c
@@ -242,7 +242,7 @@ struct geometry {
     uint32_t boot_lba;		/* LBA of bootstrap code */
     uint8_t type;		/* Type byte for INT 13h AH=08h */
     uint8_t driveno;		/* Drive no */
-    uint16_t sector_size;	/* Sector size in bytes (512 vs. 2048) */
+    uint8_t sector_shift;	/* Sector size as a power of 2 */
     const char *hsrc, *ssrc;	/* Origins of H and S geometries */
 };
 
@@ -322,13 +322,13 @@ static const struct geometry *get_disk_image_geometry(uint32_t where,
 
     printf("command line: %s\n", shdr->cmdline);
 
-    hd_geometry.sector_size = 512;	/* Assume floppy/HDD at first */
+    hd_geometry.sector_shift = 9;	/* Assume floppy/HDD at first */
 
     offset = 0;
     if (CMD_HASDATA(p = getcmditem("offset")) && (v = atou(p)))
 	offset = v;
 
-    sectors = xsectors = (size - offset) >> 9;
+    sectors = xsectors = (size - offset) >> hd_geometry.sector_shift;
 
     hd_geometry.hsrc = "guess";
     hd_geometry.ssrc = "guess";
@@ -372,8 +372,7 @@ static const struct geometry *get_disk_image_geometry(uint32_t where,
 	    hd_geometry.h = 255;
 	    hd_geometry.s = 15;
 	    /* 2048-byte sectors, so adjust the size and count */
-	    hd_geometry.sector_size = 2048;
-	    sectors = (size - hd_geometry.offset) >> 11;
+	    hd_geometry.sector_shift = 11;
 	    break;
 	case 1:		/* 1.2 MB floppy  */
 	    hd_geometry.s = 15;
@@ -393,9 +392,10 @@ static const struct geometry *get_disk_image_geometry(uint32_t where,
 	case 4:
 	    hd_geometry.driveno = 0x80;
 	    hd_geometry.type = 0;
-	    sectors = (size - hd_geometry.offset) >> 9;
 	    break;
 	}
+	sectors = (size - hd_geometry.offset) >> hd_geometry.sector_shift;
+
 	/* For HDD emulation, we figure out the geometry later. Otherwise: */
 	if (hd_geometry.s) {
 	    hd_geometry.hsrc = hd_geometry.ssrc = "El Torito";
@@ -413,7 +413,7 @@ static const struct geometry *get_disk_image_geometry(uint32_t where,
 	hd_geometry.h = dosemu.h;
 	hd_geometry.s = dosemu.s;
 	hd_geometry.offset += dosemu.offset;
-	sectors = (size - hd_geometry.offset) >> 9;
+	sectors = (size - hd_geometry.offset) >> hd_geometry.sector_shift;
 
 	hd_geometry.hsrc = hd_geometry.ssrc = "DOSEMU";
     }
@@ -466,7 +466,7 @@ static const struct geometry *get_disk_image_geometry(uint32_t where,
 
 	if (!(max_h | max_s)) {
 	    /* No FAT filesystem found to steal geometry from... */
-	    if ((sectors < 4096 * 2) && (hd_geometry.sector_size == 512)) {
+	    if ((sectors < 4096 * 2) && (hd_geometry.sector_shift == 9)) {
 		int ok = 0;
 		unsigned int xsectors = sectors;
 
@@ -778,7 +778,7 @@ void setup(const struct real_mode_args *rm_args_ptr)
 
     /* Choose the appropriate installable memdisk hook */
     if (do_eltorito) {
-	if (geometry->sector_size == 2048) {
+	if (geometry->sector_shift == 11) {
 	    bin_size = (int)&_binary_memdisk_iso_2048_bin_size;
 	    memdisk_hook = (char *)&_binary_memdisk_iso_2048_bin_start;
 	} else {
@@ -817,6 +817,7 @@ void setup(const struct real_mode_args *rm_args_ptr)
     pptr->sectors = geometry->s;
     pptr->mdi.disksize = geometry->sectors;
     pptr->mdi.diskbuf = ramdisk_image + geometry->offset;
+    pptr->mdi.sector_shift = geometry->sector_shift;
     pptr->statusptr = (geometry->driveno & 0x80) ? 0x474 : 0x441;
 
     pptr->mdi.bootloaderid = shdr->type_of_loader;
@@ -912,7 +913,7 @@ void setup(const struct real_mode_args *rm_args_ptr)
 	     * for INT 0x13, AH=0x48 "EDD Get Disk Parameters" call on an
 	     * El Torito ODD.  Check for 2048-byte sector size
 	     */
-	    if (geometry->sector_size != 2048)
+	    if (geometry->sector_shift != 11)
 		pptr->edd_dpt.flags |= 0x0002;	/* Geometry valid */
 	}
 	if (!(geometry->driveno & 0x80)) {