Re: [Xen-devel] Linux as 32-bit Dom0?

[Juergen Gross <jgross@xxxxxxxx>]

On 22/11/17 15:05, Jan Beulich wrote:
> Jürgen, Boris,
> 
> am I trying something that's not allowed, but selectable via Kconfig?
> On system with multiple IO-APICs (I assume that's what triggers the
> problem) I get
> 
> Kernel panic - not syncing: Max apic_id exceeded!

Generally I don't think 32 bit dom0 is forbidden, but rarely used. I
wouldn't be too sad in case we'd decide to drop that support. ;-)

Can you please be a little bit more specific?

How many IOAPICs? From the code I guess this is an INTEL system with not
too recent IOAPIC versions (<0x14)?

Having a little bit more of the boot log might help, too.


Juergen

> 
> CPU: 0 PID: 0 Comm: swapper Not tainted 4.14.1-2017-11-21-xen0 #6
> Hardware name: ...
> Call Trace:
>  ? show_stack+0x20/0x50
>  ? dump_stack+0x7e/0xc0
>  ? panic+0x99/0x220
>  ? io_apic_get_unique_id+0x207/0x210
>  ? __raw_callee_save_xen_restore_fl+0x6/0x8
>  ? xen_flush_tlb_single+0x6f/0x80
>  ? set_pte_vaddr+0xef/0x110
>  ? xen_io_apic_read+0x36/0x90
>  ? mp_register_ioapic+0x2b7/0x410
>  ? acpi_os_map_iomem+0x14d/0x210
>  ? acpi_parse_ioapic+0x6b/0x6f
>  ? acpi_parse_entries_array+0xa1/0x16d
>  ? acpi_tb_get_table+0x95/0x9d
>  ? acpi_ut_release_mutex+0x109/0x10e
>  ? acpi_table_parse_entries_array+0x98/0xa8
>  ? acpi_table_parse_entries+0x30/0x35
>  ? acpi_boot_init+0x65/0x65
>  ? acpi_table_parse_madt+0x1b/0x1f
>  ? acpi_boot_init+0x65/0x65
>  ? acpi_parse_madt_ioapic_entries+0x4a/0x119
>  ? mutex_lock+0x8/0x30
>  ? acpi_process_madt+0xbe/0x105
>  ? acpi_boot_init+0x3d/0x65
>  ? setup_arch+0x67a/0x83f
>  ? 0xc1000000
>  ? start_kernel+0x46/0x361
>  ? x86_early_init_platform_quirks+0x4d/0x90
>  ? i386_start_kernel+0x22/0x88
>  ? xen_start_kernel+0x453/0x639
> (XEN) Hardware Dom0 crashed: 'noreboot' set - not rebooting.
> 
> I admit I have a few custom patches in that tree, but I'm reasonably
> certain that none of them comes even close to having such an effect.
> 
> Jan
> 


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