Re: [Xen-devel] [PATCH] x86/setup: do not relocate below the end of current Xen image placement

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Mon, Nov 27, 2017 at 04:58:52PM +0000, Andrew Cooper wrote:
> On 27/11/17 15:41, Daniel Kiper wrote:
> > If it is possible we would like to have the Xen image higher than the
> > booloader put it and certainly do not overwrite the Xen code and data
> > during copy/relocation. Otherwise the Xen may crash silently at boot.
> >
> > Signed-off-by: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
>
> Actually, there is a second related bug which I've only just got to the
> bottom of, and haven't had time to fix yet.
>
> (XEN) Bootloader: GRUB 2.02
> (XEN) Command line: hvm_fep com1=115200,8n1 console=com1,vga
> dom0_mem=2048M,max:2048M watchdog ucode=scan dom0_max_vcpus=8
> crashkernel=192M,below=4G
> (XEN) Xen image load base address: 0xaba00000
> (XEN) Video information:
> (XEN)  VGA is text mode 80x25, font 8x16
> (XEN)  VBE/DDC methods: none; EDID transfer time: 0 seconds
> (XEN)  EDID info not retrieved because no DDC retrieval method detected
> (XEN) Disc information:
> (XEN)  Found 1 MBR signatures
> (XEN)  Found 1 EDD information structures
> (XEN) Xen-e820 RAM map:
> (XEN)  0000000000000000 - 000000000009bc00 (usable)
> (XEN)  000000000009bc00 - 00000000000a0000 (reserved)
> (XEN)  00000000000e0000 - 0000000000100000 (reserved)
> (XEN)  0000000000100000 - 00000000ac209000 (usable)
> (XEN)  00000000ac209000 - 00000000aeb99000 (reserved)
> (XEN)  00000000aeb99000 - 00000000aeb9d000 (ACPI NVS)
> (XEN)  00000000aeb9d000 - 00000000aecd1000 (reserved)
> (XEN)  00000000aecd1000 - 00000000aecd4000 (ACPI NVS)
> (XEN)  00000000aecd4000 - 00000000aecf5000 (reserved)
> (XEN)  00000000aecf5000 - 00000000aecf6000 (ACPI NVS)
> (XEN)  00000000aecf6000 - 00000000aed24000 (reserved)
> (XEN)  00000000aed24000 - 00000000aef2f000 (ACPI NVS)
> (XEN)  00000000aef2f000 - 00000000aefed000 (ACPI data)
> (XEN)  00000000aefed000 - 00000000af000000 (usable)
> (XEN)  00000000af000000 - 00000000b0000000 (reserved)
> (XEN)  00000000f8000000 - 00000000fc000000 (reserved)
> (XEN)  00000000fec00000 - 00000000fec01000 (reserved)
> (XEN)  00000000fed19000 - 00000000fed1a000 (reserved)
> (XEN)  00000000fed1c000 - 00000000fed20000 (reserved)
> (XEN)  00000000fee00000 - 00000000fee01000 (reserved)
> (XEN)  00000000ff400000 - 0000000100000000 (reserved)
> (XEN)  0000000100000000 - 0000000850000000 (usable)
> (XEN) Kdump: DISABLED (failed to reserve 192MB (196608kB) at 0xa0200000)
> (XEN) ACPI: RSDP 000F0410, 0024 (r2 INTEL )
>
> When booting with Grub2 capable of locating Xen at its preferred
> location, the calculation for the kexec region fails, because the
> current location of Xen isn't taken into account.
>
> The end of the chosen kexec region (0xa0200000 + 0x0c000000) overlaps
> with the bottom of the Xen image.

I have a feeling that you can trigger this also when xen.efi
is launched directly from EFI. However, this may require some
fiddling with crashkernel values.

Daniel

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