[Qemu-devel] [Bug 740895] [NEW] qemu freeze when loading msdos with EMM386.EXE NOEMS HIGHSCAN

[Guillaume Robin]

Public bug reported:

Qemu version used : 0.11.2 and 0.14.0
Guest : Ms-Dos 6.2
Host : Ubuntu 10.04 with 2.6.32-29-generic SMP i686
Starting Qemu with command : qemu -hda dos.img -cpu 486 -m 16

When I start msDos under Qemu with the option (in CONFIG.SYS) 
DEVICE=C:\DOS\EMM386.EXE NOEMS HIGHSCAN
the guest freeze.
If I remove "HIGHSCAN" system is booting (but my software is not working).

The whole thing is working on a real computer with a 486 with 16Mb ram
or a PII.

"HIGHSCAN switch allows EMM386.EXE to map expanded memory pages or upper
memory blocks (UMBs) over portions of the upper memory area (UMA) used
by system read-only memory " from http://support.microsoft.com/kb/96522
/en-us

I add some traces inside "default_ioport_read" in ioport.c, but I don't
see any access to F000h-F7FFh like said in ms help.

Before the system hung, there is access to dma1, dma page register and
dma2 :

inb : 0087 00
outb: 000c 00
inb : 0000 00
inb : 0000 00
inb : 0001 00
inb : 0001 00
inb : 0083 00
outb: 000c 00
inb : 0002 00
inb : 0002 00
inb : 0003 00
inb : 0003 00
inb : 0081 00
outb: 000c 00
inb : 0004 00
inb : 0004 00
inb : 0005 00
inb : 0005 00
inb : 0082 00
outb: 000c 00
inb : 0006 00
inb : 0006 00
inb : 0007 00
inb : 0007 00
inb : 008b 00
outb: 00d8 00
inb : 00c4 00
inb : 00c4 00
inb : 00c6 00
inb : 00c6 00
inb : 0089 00
outb: 00d8 00
inb : 00c8 00
inb : 00c8 00
inb : 00ca 00
inb : 00ca 00
inb : 008a 00
outb: 00d8 00
inb : 00cc 00
inb : 00cc 00
inb : 00ce 00
inb : 00ce 00
outb: 000c 00
outb: 00d8 00

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/740895

Title:
  qemu freeze when loading msdos with EMM386.EXE NOEMS HIGHSCAN

Status in QEMU:
  New

Bug description:
  Qemu version used : 0.11.2 and 0.14.0
  Guest : Ms-Dos 6.2
  Host : Ubuntu 10.04 with 2.6.32-29-generic SMP i686
  Starting Qemu with command : qemu -hda dos.img -cpu 486 -m 16

  When I start msDos under Qemu with the option (in CONFIG.SYS) 
  DEVICE=C:\DOS\EMM386.EXE NOEMS HIGHSCAN
  the guest freeze.
  If I remove "HIGHSCAN" system is booting (but my software is not working).

  The whole thing is working on a real computer with a 486 with 16Mb ram
  or a PII.

  "HIGHSCAN switch allows EMM386.EXE to map expanded memory pages or
  upper memory blocks (UMBs) over portions of the upper memory area
  (UMA) used by system read-only memory " from
  http://support.microsoft.com/kb/96522/en-us

  I add some traces inside "default_ioport_read" in ioport.c, but I
  don't see any access to F000h-F7FFh like said in ms help.

  Before the system hung, there is access to dma1, dma page register and
  dma2 :

  inb : 0087 00
  outb: 000c 00
  inb : 0000 00
  inb : 0000 00
  inb : 0001 00
  inb : 0001 00
  inb : 0083 00
  outb: 000c 00
  inb : 0002 00
  inb : 0002 00
  inb : 0003 00
  inb : 0003 00
  inb : 0081 00
  outb: 000c 00
  inb : 0004 00
  inb : 0004 00
  inb : 0005 00
  inb : 0005 00
  inb : 0082 00
  outb: 000c 00
  inb : 0006 00
  inb : 0006 00
  inb : 0007 00
  inb : 0007 00
  inb : 008b 00
  outb: 00d8 00
  inb : 00c4 00
  inb : 00c4 00
  inb : 00c6 00
  inb : 00c6 00
  inb : 0089 00
  outb: 00d8 00
  inb : 00c8 00
  inb : 00c8 00
  inb : 00ca 00
  inb : 00ca 00
  inb : 008a 00
  outb: 00d8 00
  inb : 00cc 00
  inb : 00cc 00
  inb : 00ce 00
  inb : 00ce 00
  outb: 000c 00
  outb: 00d8 00