Re: [Qemu-devel] [PATCH v2 1/2] hmp: dump ids including socket-id, core-id and so on for 'info registers'

[Igor Mammedov]

On Wed, 26 Jul 2017 14:50:10 -0300
Eduardo Habkost <address@hidden> wrote:

> On Wed, Jul 26, 2017 at 04:27:54PM +0200, Igor Mammedov wrote:
> > On Wed, 26 Jul 2017 11:01:14 -0300
> > Eduardo Habkost <address@hidden> wrote:
> >   
> > > On Wed, Jul 26, 2017 at 02:18:36AM -0400, Yi Wang wrote:  
> > > > This patch add output of CPUs' socket-id, core-id, thread-id and
> > > > apic-id for 'info registers', which can be used for querying other
> > > > hmp commands.
> > > > 
> > > > Signed-off-by: Yi Wang <address@hidden>
> > > > Signed-off-by: Yun Liu <address@hidden>
> > > > ---
> > > >  target/i386/helper.c | 8 ++++++++
> > > >  1 file changed, 8 insertions(+)
> > > > 
> > > > diff --git a/target/i386/helper.c b/target/i386/helper.c
> > > > index f63eb3d..a52f300 100644
> > > > --- a/target/i386/helper.c
> > > > +++ b/target/i386/helper.c
> > > > @@ -416,6 +416,14 @@ void x86_cpu_dump_state(CPUState *cs, FILE *f, 
> > > > fprintf_function cpu_fprintf,
> > > >      int eflags, i, nb;
> > > >      char cc_op_name[32];
> > > >      static const char *seg_name[6] = { "ES", "CS", "SS", "DS", "FS", 
> > > > "GS" };
> > > > +    APICCommonState *s = APIC_COMMON(cpu->apic_state);
> > > > +
> > > > +    if (!s) {
> > > > +        cpu_fprintf(f, "local apic state not available\n");
> > > > +        return;
> > > > +    }   
> > > 
> > > This breaks "info registers" on 486:
> > > 
> > >   $ ./x86_64-softmmu/qemu-system-x86_64 -cpu 486 -display none -monitor 
> > > stdio
> > >   QEMU 2.9.90 monitor - type 'help' for more information
> > >   (qemu) info registers
> > >   local apic state not available
> > >   (qemu)
> > > 
> > > You can simply use X86CPU::apic_id.  The field is set to a consistent 
> > > value
> > > even if there's no guest-visible APIC, because we use it as a VCPU 
> > > identifier
> > > internally.
> > > 
> > > However, I'm not sure "info registers" is the right place to print this 
> > > info.
> > > I think "info cpus" would be a more obvious place, but it would probably 
> > > make
> > > its output too long.
> > > We could implement something like "info cpus -v", but: the "apic-id" info 
> > > would
> > > be redundant as soon as we replace "CPU #<cpu_index>" with "CPU 
> > > #<arch_id>",  
> > lets do it in 'info registers' for now, it looks like obvious place to 
> > display
> > yet another cpu register.  
> 
> I think the APIC ID is useful to be printed by "info cpus" and
> "info registers", but socket/core/thread IDs don't belong to
> "info registers" and can be printed by "info qtree".
> 
> But I don't see a point in adding APIC ID temporarily to "info
> registers" if it will be made redundant before the next release
> (hopefully) when we start using arch_id on the "CPU #%d" lines.
> (It is already too late for 2.10.)
we can't switch to arch_id unless it's done for all related commands in one go.

> 
> > 
> >   
> > > and other details like socket/core/thread could just appear on "info 
> > > qtree".  
> > cpus are not displayed in 'info qtree'  
> 
> We can fix that.
qtree is based on qdev bus hierarchy and CPUs (at least for i386 are bus-less),
not sure I'd like to back and tie them to some 'bus' again