[SeaBIOS] [Bochs-developers] Bochs cvs + SeaBIOS git master + FreeDOS = slow load + invalid opcode

[Stanislav Shwartsman]

<So, at first glance it looks like Bochs isn't doing floppy DMA when
<the cpu is in the "hlt" state.  This causes SeaBIOS to timeout the
<transfer.

Right, Bochs CPU won't handle floppy DMA when halted.
The CPU is just running busy loop until it finds pending INIT/NMI/SMI or
INTR with EFLAGS.IF set.
Should HRQ to take CPU out of halt state ?
Or just handle the DEV_dma_raise_hlda and stay in halt state ?

Stanislav


-----Original Message-----
From: Kevin O'Connor [mailto:kevin at koconnor.net] 
Sent: Tuesday, January 12, 2010 6:13 AM
To: Sebastian Herbszt
Cc: bochs-developers at lists.sourceforge.net; seabios at seabios.org
Subject: Re: [Bochs-developers] [SeaBIOS] Bochs cvs + SeaBIOS git master +
FreeDOS = slow load + invalid opcode

On Mon, Jan 11, 2010 at 10:28:49PM +0100, Sebastian Herbszt wrote:
> The problem occurs on
> COMMAND: [e6] [04] [03] [01] [01] [02] [12] [00] [ff]
> 
> Debug output with Bochs BIOS
> 
[...]
> 00131978879d[FDD  ] read!
> 00131978879d[FDD  ] floppy_xfer: drive=0, offset=64512, bytes=512,
direction=from floppy
[...]
> 00135765306d[FDD  ] floppy_xfer: drive=0, offset=73216, bytes=512,
direction=from floppy
> 00135988037d[FDD  ] <<READ DONE>>

I'm guessing the first column is a timer - it shows a delta of 4009158
from floppy start to end.

> Debug output with SeaBIOS
> 
> 01484895591d[FDD  ] read!
[...]
> 01484895591d[FDD  ] floppy_xfer: drive=0, offset=64512, bytes=512,
direction=from floppy
[...]
> 01643752509d[FDD  ] floppy_xfer: drive=0, offset=70656, bytes=512,
direction=from floppy
> 01646422786d[FDD  ] read(): during command 0xe6, port 0x03f2 returns 0x1c

The delta here is 161527195.

Also, if you count the "loop" reports you'll see there are 37 of them
- the same number as FLOPPY_MOTOR_TICKS in src/floppy.c.

So, at first glance it looks like Bochs isn't doing floppy DMA when
the cpu is in the "hlt" state.  This causes SeaBIOS to timeout the
transfer.

-Kevin

----------------------------------------------------------------------------
--
This SF.Net email is sponsored by the Verizon Developer Community
Take advantage of Verizon's best-in-class app development support
A streamlined, 14 day to market process makes app distribution fast and easy
Join now and get one step closer to millions of Verizon customers
http://p.sf.net/sfu/verizon-dev2dev 
_______________________________________________
bochs-developers mailing list
bochs-developers at lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/bochs-developers