Re: [RFC PATCH 10/11] target/ppc: created tcg-stub.c file

[Bruno Piazera Larsen]

On 12/05/2021 15:39, Richard Henderson wrote:

> On
>       5/12/21 9:08 AM, Bruno Larsen (billionai) wrote:
>       
> > +++ b/target/ppc/tcg-stub.c
> >         
> >         @@ -0,0 +1,33 @@
> >         
> >         +
> >         
> >         +#include "qemu/osdep.h"
> >         
> >       
>       
>       All files get copyright boilerplate.
>       
>       
> > +#include "exec/hwaddr.h"
> >         
> >         +#include "cpu.h"
> >         
> >         +#include "hw/ppc/spapr.h"
> >         
> >         +
> >         
> >         +hwaddr ppc_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
> >         
> >         +{
> >         
> >         +    return 0;
> >         
> >         +}
> >         
> >       
>       
>       This is used by gdbstub.
>       
>       
>       If there's a way for kvm to convert a virtual address to a
>       physical address using the hardware, then use that.  I suspect
>       there is not.
>       
>       
>       Otherwise, you have to keep all of the mmu page table walking
>       stuff for kvm as well as tcg.  Which probably means that all of
>       the other stuff that you're stubbing out is used or usable as
>       well.
>       
>

From what I can tell, KVM can't do it, so we'll have to extract the function. Looking at it, the main problem is that it might call get_physical_address and use struct mmu_ctx_t, if the mmu_model isn't one of: POWERPC_MMU_64B, POWERPC_MMU_2_03, POWERPC_MMU_2_06, POWERPC_MMU_2_07, POWERPC_MMU_3_00, POWERPC_MMU_32B, POWERPC_MMU_601.

Is it possible that a machine with an mmu not listed in here could build a !TCG version of qemu? if it's not possible, we can separate that part into a separate function left in mmu_helper.c and move the rest to somewhere else.

Looking at dump_mmu and ppc_tlb_invalidate_all, looks like we need to move enough code that it make sense to create an mmu_common.c for common code. Otherwise, it's probably easier to compile all of mmu_helper.c instead of picking those functions out.

--

Bruno Piazera Larsen
Instituto de Pesquisas ELDORADO
Departamento Computação Embarcada
Analista de Software Trainee
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