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-rw-r--r--com32/modules/chain.c25
1 files changed, 22 insertions, 3 deletions
diff --git a/com32/modules/chain.c b/com32/modules/chain.c
index b93f38ed..89489d18 100644
--- a/com32/modules/chain.c
+++ b/com32/modules/chain.c
@@ -76,6 +76,10 @@
* equivalent to seg=0x70 file=<loader> sethidden,
* used with DOS' io.sys.
*
+ * drmk=<loader>
+ * Similar to msdos=<loader> but prepares the special options
+ * for the Dell Real Mode Kernel.
+ *
* grub=<loader>
* same as seg=0x800 file=<loader> & jumping to seg 0x820,
* used with GRUB Legacy stage2 files.
@@ -1707,16 +1711,31 @@ int main(int argc, char *argv[])
* We only really need 4 new, usable bytes at the end.
*/
int tsize = (data[ndata].size + 19) & 0xfffffff0;
+ const union syslinux_derivative_info *sdi;
+
+ sdi = syslinux_derivative_info();
+ /* We should lookup the Syslinux partition offset and use it */
+ fs_lba = *sdi->disk.partoffset;
+ /*
+ * fs_lba should be verified against the disk as some DRMK
+ * variants will check and fail if it does not match
+ */
+ dprintf(" fs_lba offset is %d\n", fs_lba);
+ /* DRMK only uses a DWORD */
+ if (fs_lba > 0xffffffff) {
+ error("LBA very large; Only using lower 32 bits; DRMK will probably fail\n");
+ }
regs.ss = regs.fs = regs.gs = 0; /* Used before initialized */
if (!realloc(data[ndata].data, tsize)) {
error("Failed to realloc for DRMK\n");
- goto bail;
+ goto bail; /* We'll never make it */
}
data[ndata].size = tsize;
- /* ds:[bp+28] must be 0x0000003f */
+ /* ds:bp is assumed by DRMK to be the boot sector */
+ /* offset 28 is the FAT HiddenSectors value */
regs.ds = (tsize >> 4) + (opt.seg - 2);
/* "Patch" into tail of the new space */
- *(int *)(data[ndata].data + tsize - 4) = 0x0000003f;
+ *(int *)(data[ndata].data + tsize - 4) = (int)(fs_lba & 0xffffffff);
}
ndata++;