Re: [Qemu-devel] address translation

["andrzej zaborowski" <balrogg@gmail.com>]

On 13/07/07, Shashidhar Mysore <shashimc@gmail.com> wrote:
> Hello group,
>
> I have two questions, both regarding the virtual-physical translation of
> addresses (all in the virtual machine context).
>
> 1>
> Can somebody tell me if the program counter value available in the following
> snippet from target-i386/translate.c
> is virtual or physical? I learnt it may be virtual, in which case is there a
> way to extract the physical address corresponding to the
> virtual address, or if it is physical, then is there a way to translate to
> its virtual address (within the virtual machine context)?

It is virtual, I think cpu_get_phys_page_debug() + the offset should
give you physical.

>
> ************************************************
> /* convert one instruction. s->is_jmp is set if the translation must
>    be stopped. Return the next pc value */
> static target_ulong disas_insn(DisasContext *s, target_ulong pc_start)
> {
>     int b, prefixes, aflag, dflag;
>     int shift, ot;
>     int modrm, reg, rm, mod, reg_addr, op, opreg, offset_addr, val;
>     target_ulong next_eip, tval;
>     int rex_w, rex_r;
>
>     s->pc = pc_start;   // This s->pc is what I am using to extract all
> executed PC values

This s->pc doesn't correspond to executed PC values, qemu is a translator.

> ************************************************
>
>
> 2>
> Second question I have is - Within the functions from target-i386/ops_mem.h
> for example,
>
> void OPPROTO glue(glue(op_ldub, MEMSUFFIX), _T0_A0)(void)
>  {
>      T0 = glue(ldub, MEMSUFFIX)(A0);
>  }
>
> Is A0 the physical address? or is it virtual?
> And how to I translate from one to another in either case?

Also virtual.

Regards