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>

diff --git a/doc/memdisk.txt b/doc/memdisk.txt
index c7244ab..b8ed9ae 100644 (file)
--- a/doc/memdisk.txt
+++ b/doc/memdisk.txt
@@ -190,13 +190,14 @@ The MEMDISK info structure currently contains:
        [ES:DI+2]       byte    MEMDISK minor version
        [ES:DI+3]       byte    MEMDISK major version
        [ES:DI+4]       dword   Pointer to MEMDISK data in high memory
-       [ES:DI+8]       dword   Size of MEMDISK data in 512-byte sectors
+       [ES:DI+8]       dword   Size of MEMDISK data in sectors
        [ES:DI+12]      16:16   Far pointer to command line
        [ES:DI+16]      16:16   Old INT 13h pointer
        [ES:DI+20]      16:16   Old INT 15h pointer
        [ES:DI+24]      word    Amount of DOS memory before MEMDISK loaded
        [ES:DI+26]      byte    Boot loader ID
-       [ES:DI+27]      byte    Currently unused
+       [ES:DI+27]      byte    Sector size as a power of 2
+                               (If zero, assume 512-byte sectors)
        [ES:DI+28]      word    If nonzero, offset (vs ES) to installed DPT
                                This pointer+16 contains the original INT 1Eh
 

diff --git a/memdisk/mstructs.h b/memdisk/mstructs.h
index c2e6352..fecbff4 100644 (file)
--- 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 20b48c4..3f69cd3 100644 (file)
--- 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)) {

diff --git a/utils/memdiskfind.c b/utils/memdiskfind.c
index 45d54bc..f2086b2 100644 (file)
--- a/utils/memdiskfind.c
+++ b/utils/memdiskfind.c
@@ -60,7 +60,13 @@ static bool valid_mbft(const struct mBFT *mbft, size_t space)
 
 static void output_params(const struct mBFT *mbft)
 {
-    printf("%u,%u\n", mbft->mdi.diskbuf, mbft->mdi.disksize);
+    int sector_shift = mbft->mdi.sector_shift;
+
+    if (!sector_shift)
+       sector_shift = 9;
+
+    printf("%#x,%#x\n",
+          mbft->mdi.diskbuf, mbft->mdi.disksize << sector_shift);
 }
 
 int main(int argc, char *argv[])