[virt-layer] score/libcpu split (i386)

[Philipp Eppelt]

On 05/15/2013 03:55 PM, Gedare Bloom wrote:
> On Tue, May 14, 2013 at 11:55 AM, Philipp Eppelt
> <philipp.eppelt at mailbox.tu-dresden.de> wrote:
>> Hi,
>>
>> I looked into the libcpu/sh dir to understand how the split of the CPU code
>> between score/cpu and libcpu/ works.
>>
>> My approach for the i386 arch brings some changes to existing files:
>>
>> * score/i386/rtems/score/cpu.h
>> * score/i386/cpu.c
>> * score/i386/rtems/score/interrupts.h
>>
>> The list of functions, sensitive for a virtualization environment is rather
>> short (up until now):
>>
>> * _CPU_ISR_Set_level (cpu.h)
>> * _CPU_Fatal_halt (cpu.h)
>> * _CPU_Thread_Idle_body (cpu.c)
>> * everything in interrupt.h
>>
>> For a full and up to date list, check [0].
>>
>> I want to introduce new directories containing the right versions for the
>> above mentioned functions:
>> * libcpu/i386/virt-pok
>> * libcpu/i386/{native|hw|nonvirt|..}
>>
> Why "virt-pok" and not just "virt" or "virtual"?
>
> Probably the other side (native/hw/nonvirt) can just be called
> "shared/score". And you would put the virtualized functionality in the
> "virt-pok/score".
>

I would refrain from calling it shared/, as it would imply shared 
functionality with virtual/. At least that my understanding of the usage 
in all other parts of the system.
Maybe native is the best description as it opposes virtual.

*libcpu/i386/virtual
*libcpu/i386/native


>> Which part do I need to explain in more detail?
> Probably the justification for which code is identified as
> sensitive/privileged, and what is not.

The mentioned functions contain privileged instructions: hlt, cli, sti
These functions cannot be executed in a virtual environment and must be 
replaced with environment specific function calls.


Regards,
Philipp