Old TORO

Since 2006, the year in which TORO objectives were modified, the TORO OS project corresponding to the version 1.xx was discontinued. These versions achieved a great success in terms of functionality. The most stable version was 1.1.3, sometimes I see the source of those versions and I feel very sorry of have abandoned it, however it was impossible to me to continue with both projects simultaneously. So I decided to make a small tribute to those versions. For that i will show next how to test TORO 1.1.3 through BOCHS. I've put some screenshots for you to observe the beauty of a shell in PASCAL. Enjoy it!

For these simulations is necessary x86 Bochs, remember that the 1.1.3 version is only for 32 bits. Here I include the torobch.bxrc file contents.

megs: 256

romimage: file=BIOS-bochs-latest, address=0xf0000

floppya: 1_44=toro-1.1.3.img, status=inserted

boot: floppy

It is necessary to download the toro-1.1.3 image from the link:

http://sourceforge.net/projects/toro/files/images/toro-1.1.3/toro-1.1.3.img/download

If everything is allright, the first window you will see when execute BOCHS will be:

Corresponds the GRUB bootloader, there you select TORO-1.1.3 and press enter.

It will start to load the OS and then the Shell:

We are ready to enter commands on TORO. The first command we will see is the ls that, as you already know, lists the actual directory.

Now we go to the directory where finds TORO's source using cd.

And we are going to run echo printk.pas, this will display the file content on screen.

You can see all Shell commands at /BIN directory, these are:

Running reboot the system is closed and we can turn off the virtual machine.

I hope you enjoyed it, make your own experiences running commands. You can also burn the image in a 3 ½ floppy and try it in a real machine.

Attention: Versions 1.x.x have no relation with version 0.xx, they are different things.

Matias E. Vara

www.torokernel.org

Threads migration without Lock in Toro

In a Multicore environment, the programmer needs to create local and remote threads. In TORO create a remote threads is easy, you just have to use BeginThread() with the appropriate CPU identification. On that basis, there are two important procedures in TORO:

- Thread Emigrating: is when the threads are created in a remote processor.
- Thread Inmigrating: is when the guest processor enque in its scheduler the threads that they are comming from others processors.

This is the unique kernel point which needs syncronization between the cores. The mechanism is called "Exchange Slot" and it works without any atomic operation. In this case it used for send and receiv threads but it works with any kind of data.

For every processor in TORO there is an structure called TSchedulerExchangeSlot:

TSchedulerExchangeSlot = record
DispatcherArray: array[0..MAX_CPU-1] of PThread;
EmigrateArray: array[0..MAX_CPU-1] of PThread;
end;

Where MAX_CPU is the number of processors and PThread is a pointer to TThread structure. From the structure declaration we can see that every processor has two arrays

(DispatcherArray y EmigrateArray), and every entry in the array is a pointer to a thread´s queu.

The procedure to send threads to remote processor has three stages:
1-The user calls to BeginThread()for create a new one, if the parameter CPUID is different to local CPU then the kernel enque it to DispatcherArray[CPUID].
2-During Scheduling (cause SysThreadSwitch syscall). The procedure Emigrating()moves all threads from DispatcherArray[] to EmigrateArray[] (only if EmigrateArray[] is nil)
3-During Scheduling of the Remote CPU, the procedure Inmigrating() look for a not nil entry in EmigrateArray[LocalCPUID] in every TSchedulerExchangeSlot processor structure. If it is not nil Then import all the threads to local scheduler and become EmigrateArray[LocalCpuid] to nil.
Local processor just writes and read to DispatcherArray[]. While the local and remote processor write and read to EmigrateArray[], but the access is synchronized using nil pointer.
The “Exchange Slot” doesn´t need "LOCK" instruction.


The Inmigrating and Emigrating procedures are called from the Scheduler. The scheduler makes a few system task, for example in the picture, we can see the scheduler´s flow diagram. There, first it calls Inmigrating(), after that it calls Emigrating() and At the end a new thread is scheduling.


Matias E. Vara
www.torokernel.org