Re: [Qemu-devel] SMP Question

[Jonathan Phenix]

maple Chou wrote:
> Dear All,
>  I just doing my floppy toy-os project(include little bootloader). And 
> test with qemu.
> The Floppy Image is here  http://file.maple.tw/mapleos/floppy.img
>
> My problem is when I turn on the SMP option. (qemu -fda floppy.img -smp 2)
> The system will hang on bootsector (i just watch qemu monitor hang on 
> 0x7eca)
>
> And some problem with Grub+floppy image.
> Grub+HD image boot successful, but can't capture the keyboard.
>
> What's problem!?? i only run SMP case successful with linux kernel.
For your project, qemu should be considered a _tool_. Like all tools, 
you must know it's usefulness (it's easier to debug your OS on an 
emulator) but you must be very well aware that all emulators are 
accurate only up to a certain point of the actual system emulated. This 
is not to mention that qemu is not yet complete (latest official release 
is 0.8.2), there are known bugs and unimplemented features that could 
always be the source of the problem. Finally, even if qemu is able to 
boot many common SMP enabled OSes, it's not a guarantee that everything 
is perfect related to SMP in qemu.

If you believe that your code is correct and this is a bug in qemu, 
which is always possible, try with different PC emulators to see if 
there is a difference. The best thing to do is to actually test on a 
real SMP system, real hardware have a final say on what should work and 
what doesn't.

Finally, developing an OS is not a small task, perhaps you should focus 
on single processor systems first which are a lot easier to design and 
debug for and then focus on SMP systems later on.

Regards,

- Jonathan
> Best Regards
>
>   ~maple
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