RE: [Xen-devel] smp booting query

["Pradeep Singh, TLS-Chennai" <pradeep_s@xxxxxx>]

-----Original Message-----
From: M.A. Williamson on behalf of Mark Williamson
Sent: Sun 11-Mar-07 9:28 AM
To: xen-devel@xxxxxxxxxxxxxxxxxxx
Cc: Petersson, Mats; Pradeep Singh, TLS-Chennai
Subject: Re: [Xen-devel] smp booting query

On Friday 09 March 2007 13:40, Petersson, Mats wrote:
> > -----Original Message-----
> > From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> > [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> > Pradeep Singh, TLS-Chennai
> > Sent: 09 March 2007 13:27
> > To: xen-devel@xxxxxxxxxxxxxxxxxxx
> > Subject: [Xen-devel] smp booting query
> >
> >
> > hi all,
> >
> > My query is related to xen-3.0.3.
> >
> > 1. Xen does not supports SMP booting , right?
> >    Is it true for both domU and dom0?
>
> I'm pretty sure that 3.0.3 supports SMP in boht Dom0 and para-virtual
> DomU.

Yep.  The entire 3.x.y series has supported SMP domUs and dom0 (although dom0
SMP is not the recommended way of doing things).

There are occasional documents floating round on the web saying that "Xen"
only supports SMP hosts and not SMP guests - these mostly date back to the
Xen 1 and Xen 2 series (or are referring to pre-3.0.3 HVM support which was
UP only)

Hope that helps clarify the current state for you Pradeep.

Thanks Mark, definitely this cleared my doubt.

Thank you all.

pradeep
Cheers,
Mark

> It also supports SMP in HVM DomU, but I'm not sure how "automatic"
> this support is (there were some changes recently to fix ACPI
> information to tell the guest how many CPU's it's got, for example).
>
> > 2. This means start_secondary from x86_32.S is never called
> > by the hypervisor, am i right?
> >    the SECONDARY_CPU_FLAG denotes a non boot CPU here i guess?
>
> Why do you think this?
>
> > 3. If it is a secondary processor xen jumps to start_secondary.
>
> Yes.
>
> > 4. __start_xen is called irrespective of the processor. right?
>
> No, only on the first CPU, not other CPU's.
>
> > 5. On doing a nm x86_32.o , we get -
> >
> >          U __bss_start
> > 00000057 t __start
> >          U __start_xen
> >          U _end
> > 00000000 T _stext
> > 00000000 B cpu0_stack
> > 000001ac T gdt
> > 000001aa t gdt_descr
> > 00001000 T gdt_table
> > 00000000 B idle_pg_table
> > 00000000 B idle_pg_table_l2
> > 000001a4 T idt
> > 000001a2 t idt_descr
> >          U idt_table
> > 00000170 t ignore_int
> > 0000015c t int_msg
> >          U mmu_cr4_features
> > 000001b2 t nopaging_gdt_descr
> > 00000031 t not_multiboot
> > 00000010 t not_multiboot_msg
> >          U printf
> > 00000190 T stack_start
> > 00000000 T start
> > 00000108 t start_paging
> >          U start_secondary
> > 00000000 T stext
> >
> > nm shows that start_secondary is there still.Are we using it somehow ?
>
> Yes, on booting the second and further procesors...
>
> --
> Mats
>
> > or am i missing something here?
> >
> > Thanks in advance?
> >
> >
> >
> >
> > -----------------------
> > Pradeep Singh
> > Member Technical Staff
> > Core Technology Divison
> > 53, Greams Road.
> > HCL Technologies, Chennai
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel

--
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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