Re: Xen 4.2 with EFI on IBM x3650 ACPI Bug

[Konrad Rzeszutek Wilk <konrad@kernel.org>]

On Thu, Nov 08, 2012 at 09:42:58AM +0100, Jacek Konieczny wrote:
> Hello,
> 
> I am digging up the old thread  just to show a workaround for the
> IBM xSeries ACPI problem under EFI…

Great. Thx
> 
> On Fri, Oct 19, 2012 at 01:33:07PM -0400, Konrad Rzeszutek Wilk wrote:
> > On Fri, Oct 19, 2012 at 09:10:36AM +0100, Jan Beulich wrote:
> > > >>> On 19.10.12 at 01:43, Allan Scheid <avs.009@gmail.com> wrote:
> > > > Bad news, i am seeing the log output and after the xen.efi boot this still
> > > > appears on log:
> > > > 
> > > > Into messages:
> > > > Oct 18 20:27:36 lca-fw kernel: [    0.000000] ACPI BIOS Bug: Error: A valid
> > > > RSDP was not found (20120711/tbxfroot-219)
> > > > Oct 18 20:27:36 lca-fw kernel: [    0.000000] NUMA turned off
> > > > Oct 18 20:27:36 lca-fw kernel: [    3.759750] pci 0000:00:01.0: can't find
> > > > IRQ for PCI INT A; please try using pci=biosirq
> > > > Oct 18 20:27:36 lca-fw kernel: [    3.764011] pci 0000:00:1a.0: can't find
> > > > IRQ for PCI INT A; please try using pci=biosirq
> 
> IRQs are not the only problem. Only a single CPU would be detected
> without ACPI.
> 
> > > Of course - you also need the kernel to be capable of obtaining
> > > the necessary EFI information from Xen. That's a separate patch
> > > (an early port of the one we have to the pvops kernel was
> > > posted on the list a few months ago, but I don't know what its
> > > status or disposition is - Konrad?).
> 
> Yeah… it will be great to see this patch set updated and included
> upstream.

Daniel is the one that is going to take a hard look at making this
work nicely. CC-ing him here so he knows about this work-around.
> 
> > 
> > Daniel is taking a stab at it. He got the hardware. But this is good
> > to know that there is hardware that removes the RSDT from the low memory
> > and only allows to get it from the EFI. 
> 
> The firmware rather does not copy the RSDT to the low memory before
> trying to boot in the legacy BIOS mode.
> 
> 
> 
> And here is the workaround, which does not require kernel patching:
> 
> 1. Make sure your kernel is compiled with CONFIG_KEXEC=y (kexec is not
> needed for the workaround, but it enables the Linux kernel command-line
> option used later)
> 
> 2. Boot xen natively via EFI – use xen.efi not GRUB multiboot (GRUB
> EFI chainloader will be ok too)
> 
> 3. Note the RSDP address found by Xen:
> 
> # xl dmesg | grep RSDP
> (XEN) ACPI: RSDP 7F7FE014, 0024 (r2 IBM   )
> 
> 4. Add this to the dom0 kernel command-line (in the xen.cfg file used by
> xen.efi):
> 
>    acpi_rsdp=0x7F7FE014
> 
> The Linux kernel will find the ACPI RSDP and will be able to initialize
> IRQs and SMP properly.  This still won't be a proper EFI interface, so
> the 'efivars' module and 'efibootmgr' utility won't work, but this is
> not as critical as ACPI.
> 
> Greets,
>         Jacek
> 
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> 

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