I've been pouring over various logs from testbios and what my M1 Vbios
does in various conditions. Man what a bitch.
One thing I've found testbios dosen't handle properly is the 8254 system
timer. In numerious locations my Vbios is writing a 0x00 to IO 0x43 and
then does 2 reads from 0x40. S
On Thu, 2004-06-03 at 02:56, Richard Smith wrote:
>
> What i've noticed that the emulator causes the Vbios to get stuck in
> some delay loops. Eventually it probally would exit but its currently
> making my logs huge and causing the knashing of much teeth.
>
> So I'm thinking that the emulator
On Thu, 3 Jun 2004, Li-Ta Lo wrote:
> Probably we need an other way to emulate the timer.
can we just read the timer?
ron
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On Thu, 2004-06-03 at 09:35, ron minnich wrote:
> On Thu, 3 Jun 2004, Li-Ta Lo wrote:
>
> > Probably we need an other way to emulate the timer.
>
> can we just read the timer?
>
> ron
>
richard's point is that the emulator is much slower than the
timer. The delay loop is facing overflow proble
On Thu, 3 Jun 2004, Li-Ta Lo wrote:
> richard's point is that the emulator is much slower than the
> timer. The delay loop is facing overflow problem with the
> "emulated" io access to the "physical" counter.
oops, sorry. Too much email this morning. I did not read his note
carefully enough.
Ac
On Thu, Jun 03, 2004 at 03:56:29AM -0500, Richard Smith wrote:
> timer. In numerious locations my Vbios is writing a 0x00 to IO 0x43 and
> then does 2 reads from 0x40. So its latching the value of counter 0 and
> then reading it out.
Right, it also sets counter mode 0, zero detection interrupt
what about this. Build a composite timer with the top X bits coming from
TSC, and the bottom Y bits coming from the time-of-day counter. Would that
work?
ron
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OK, I finally read this in detail and I'm sorry for my noise on this
subject.
I think it would be useful to keep an 'emulated instruction count' in the
emulator, and have a virtual timer that increments very X (pick a number)
instructions. X can be constant across different architectures as we
Peter Stuge wrote:
On Thu, Jun 03, 2004 at 03:56:29AM -0500, Richard Smith wrote:
timer. In numerious locations my Vbios is writing a 0x00 to IO 0x43 and
then does 2 reads from 0x40. So its latching the value of counter 0 and
then reading it out.
Right, it also sets counter mode 0, zero detecti
ron minnich wrote:
OK, I finally read this in detail and I'm sorry for my noise on this
subject.
I think it would be useful to keep an 'emulated instruction count' in the
emulator, and have a virtual timer that increments very X (pick a number)
instructions. X can be constant across different
On Thu, 3 Jun 2004, Richard Smith wrote:
> Yes. I think it would. Got any ideas on the implementation? I'm ready
> to try an implement this.
in the main loop for instruction decode there is a single instruction
dispatch function. Create a global counter (emulate_counter?) and
increment it o
On Thu, 3 Jun 2004, Richard Smith wrote:
> This will only skip the jump (and do the BX decrement) if ax is zero.
> For ax to be zero the result of the 2's complement subtraction must be
> zero or the when the 2 reads are the same number. But I just don't see
> how this would happen repeatably
ron minnich wrote:
On Thu, 3 Jun 2004, Richard Smith wrote:
This will only skip the jump (and do the BX decrement) if ax is zero.
For ax to be zero the result of the 2's complement subtraction must be
zero or the when the 2 reads are the same number. But I just don't see
how this would happen
On Thu, Jun 03, 2004 at 03:32:58PM -0500, Richard Smith wrote:
> Peter Stuge wrote:
>
> >On Thu, Jun 03, 2004 at 03:56:29AM -0500, Richard Smith wrote:
> >
> >>timer. In numerious locations my Vbios is writing a 0x00 to IO 0x43 and
> >>then does 2 reads from 0x40. So its latching the value of c
ron minnich <[EMAIL PROTECTED]> writes:
> You can in the emulator redirect I/O port access to a function. Write the
> code to handle read/write on those ports and use the emulate_counter to
> drive the clock value.
Let me ask this quick question. Does the emulator restrict port I/O to
just the
Eric W. Biederman wrote:
You can in the emulator redirect I/O port access to a function. Write the
code to handle read/write on those ports and use the emulate_counter to
drive the clock value.
Let me ask this quick question. Does the emulator restrict port I/O to
just the resources on a particu
Richard Smith <[EMAIL PROTECTED]> writes:
> Eric W. Biederman wrote:
>
> >> You can in the emulator redirect I/O port access to a function. Write the
> >> code to handle read/write on those ports and use the emulate_counter to drive
>
> >> the clock value.
> > Let me ask this quick question. Do
Eric W. Biederman wrote:
No. It allows full access to all IO ports. Otherwise it would have never been
able to get to the system timer.
I was afraid of that.
So not only will it have to emulate x86 instructions it will have to emulate
some of the generic x86 hardware setup.
Exactly. But in this
On 8 Jun 2004, Eric W. Biederman wrote:
> ron minnich <[EMAIL PROTECTED]> writes:
> > You can in the emulator redirect I/O port access to a function. Write the
> > code to handle read/write on those ports and use the emulate_counter to
> > drive the clock value.
>
> Let me ask this quick questi
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