Re: [Qemu-devel] Poking a sun4v machine

[Blue Swirl]

On Mon, Apr 30, 2012 at 16:39, Artyom Tarasenko <address@hidden> wrote:
> Tried to boot QEMU Niagara machine with the firmware from the
> OpenSPARC T1 emulator ( www.opensparc.net/opensparc-t1/download.html )
> , and it dies very early.
> The reason: in translate.c
>
> #define hypervisor(dc) (dc->mem_idx == MMU_HYPV_IDX)
> #define supervisor(dc) (dc->mem_idx >= MMU_KERNEL_IDX)
>
> and the dc->mem_idx is initialized like this:
>
>    if (env1->tl > 0) {
>        return MMU_NUCLEUS_IDX;
>    } else if (cpu_hypervisor_mode(env1)) {
>        return MMU_HYPV_IDX;
>    } else if (cpu_supervisor_mode(env1)) {
>        return MMU_KERNEL_IDX;
>    } else {
>        return MMU_USER_IDX;
>    }
>
> Which seems to be conceptually incorrect. After reset tl == MAXTL, but
> still super- and hyper-visor bits are set, so both supervisor(dc) and
> hypervisor(dc) must return 1 which is impossible in the current
> implementation.

I don't think this is needed. The MMU index tells which TLB is used
for guest virtual to host address translations, during tl == MAXTL we
want to use hypervisor mode translations.

>
> What would be the proper way to fix it? Make mem_idx bitmap, add two
> more variables to DisasContext, or ...?
>
> Some other findings/questions:
>
>    /* Sun4v generic Niagara machine */
>    {
>        .default_cpu_model = "Sun UltraSparc T1",
>        .console_serial_base = 0xfff0c2c000ULL,
>
> Where is this address coming from? The OpenSPARC Niagara machine has a
> "dumb serial" at 0x1f10000000ULL.

I think I actually used Ontario machine definitions.

>
> And the biggest issue: UA2005 (as well as UA2007) describe a totally
> different format for a MMU TTE entry than the one sun4u CPU are using.
> I think the best way to handle it would be splitting off Niagara
> machine, and #defining MMU bits differently for sun4u and sun4v
> machines.
>
> Do we the cases in qemu where more than two (qemu-system-xxx and
> qemu-system-xxx64) binaries are produced?
> Would the name qemu-system-sun4v fit the naming convention?
>
> Artyom
>
> --
> Regards,
> Artyom Tarasenko
>
> solaris/sparc under qemu blog: http://tyom.blogspot.com/search/label/qemu