Re: New Kernel Bug (a small one)

Hi,

well this turned out to be really a bug in NDN and not the kernel.

NDN does:

INT21 (0) at 456b:0207: AX=4409, BX=0043, CX=004c, DX=6143, DS=297f, ES=3771
check if block device remote

Here it has 0x43 in BL which corresponds, following RBIL, to drive
0x40+0x43=0x83. 0x83 gives you that weird looking drive letter.

So the FreeDOS kernel says that the drive is out of range and NDN
investigates this as a critical error. The same happens with MSDOS 7.1
(aka Win98 DOS) and DRDOS 7.03 btw. I'm not sure about other DOSes.

Now we can easily work around this:

--- ke2027rc/kernel/ioctl.c	Mon Oct 21 22:40:18 2002
+++ ke2027/kernel/ioctl.c	Mon Oct 28 22:05:20 2002
@@ -199,7 +199,8 @@
 /* JPP - changed to use default drive if drive=0 */
 /* JT Fixed it */

-      CharReqHdr.r_unit = (r->BL == 0 ? default_drive : r->BL - 1);
+      CharReqHdr.r_unit = ((r->BL & 0x1f) == 0 ? default_drive :
+                           (r->BL & 0x1f) - 1);

       dpbp = get_dpb(CharReqHdr.r_unit);

But I'm not sure if this is a good idea ... We want MSDOS
compatibility, not broken DOS utility compatibility.

In the changelog at http://www.necromancer.newmail.ru/ I read for the 2.03
prerelease:

- Critical Error on drive ? bug fixed (at least in my machine)

Indeed they had this bug in NDN. Any opinions?

Bart