Changes between Version 46 and Version 47 of GSoC/2013/ParavirtualizationOfRTEMS

Timestamp:

09/19/13 18:15:07 (11 years ago)

Author:

Phipse

Comment:

HowTo? section with architecture and hypervisor port howto

GSoC/2013/ParavirtualizationOfRTEMS

@@ -448 +448 @@
 Claudio da Silva has provided one [https://gist.github.com/cdcs/5874932 here].
 
-=  More Hypervisors (L4Re) =
+=  More Hypervisors (L4Re)  =
 
 
@@ -466 +466 @@
 So it doesn't need to be present at compile time. 
 Furthermore, it we should be able to reuse the virtualpok BSP, provided we replace libpart.a with a library provided by L4Re.
-
+=  HowTo  =
+=  Run RTEMS on other hypervisors  =
+
+
+I start by explaining the build process in short, as this makes clear where to begin.
+Then I show which files are necessary to have a look at and finish with an run through the different steps. 
+Due to the differences between the hypervisors, I only give a general overview.
+
+
+RTEMS is build with for i386 and the virtualpok BSP. 
+The BSP requires a library implementing the virtualization layer functions. 
+The host has to implement the layer functions and provide the library as libpart.a in the virtpok/ directory.
+At the current state the virtualization layer provides enough functionality to compile all testsuite/samples.
+They will not all run, but ''Hello World'', ''Base_sp'' and ''Ticker'' should be working. 
+The ELF-binaries in the corresponding directories can now be used as guest binaries. 
+POK recognizes them as valid partition.
+
+
+The virtualization layer is defined by two files: virtualizationlayercpu.h and virtualizationlayerbsp.h
+The first defines the CPU related functions, mainly interrupt related, idle thread, fatal error handler.
+The second defines the board services needed by the BSP; e.g. clock, console.
+Copy these two files to your work directory on the hypervisor and implement these functions. 
+Compile these files and build a library including all hypervisor code needed (vCPU calls, VirtualMachineMonitor communication, etc.).
+Then pass it over to RTEMS into c/src/lib/libbsp/i386/virtualpok/ as ''libpart.a''.
+
+Now it is time to configure and compile RTEMS. 
+Follow the instructions in the RTEMS manual.
+To configure i386 and virtualpok make sure you find ''--target=i386-rtems4.11 --enable-rtemsbsp=virtualpok --enable-test'' in your configuration line. 
+The tests will compile the testsuite/samples.
+
+The binary in e.g. ''testsuite/samples/hello/hello.exe'' can now be used as virtual guest binary, able to communicate with your hypervisor. 
+
+=  Port this approach to other architectures  =
+
+
+I don't have a lot of knowledge about these architectures, so this HowTo is pretty abstract.
+
+First of all, you have to find out if your target architecture has so called "virtualization holes". 
+On x86 this are instructions which are able to be executed in a virtual environment, leading to a possible corruption of other virtual machines running on the hypervisor.
+Find these functions in the RTEMS source code and come up with a possibility to redesign the CPU model of this architecture.
+For i386 this led to a duplication of function guarded by a to be introduced configuration option. 
+A list of functions and files can be found above in the score-libcpu-split section.
+When your architecture is fully virtualizable you are lucky, this will reduce the work. 
+
+Other architectures do things in other ways.
+The board will look different, so you need to have a look at the drivers necessary and who is providing them. 
+The console driver is pretty basic, as it just provides inchar and outchar capability. 
+The clock driver uses the standard RTEMS environment, shared across all BSPs.
+Further, bsp_start() might change, as your architecture might not have an complicated IRQ management or you need more drivers, which need to be initialized at startup.
+And don't forget the linkcmds.
+In the best case you can just copy this from another BSP of this architecture.
 =  References  =
 
 <references/>
 
-=  Misc  =
+
+= Misc =
 
 ''Under construction''