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ACPI: introduce "acpi_rsdp=" parameter for kdump

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There is a problem with putting the first kernel in EFI virtual mode,
it is that when the second kernel comes up it tries to initialize the
EFI again and once we have put EFI in virtual mode we can not really
do that.

Actually, EFI is not necessary for kdump, we can boot the second kernel
with "noefi" parameter, but the boot will mostly fail because 2nd kernel
cannot find RSDP.

In this situation, we introduced "acpi_rsdp=" kernel parameter, so that
kexec-tools can pass the "noefi acpi_rsdp=X" to the second kernel to
make kdump works. The physical address of the RSDP can be got from
sysfs(/sys/firmware/efi/systab).

Signed-off-by: Takao Indoh <indou.takao@jp.fujitsu.com>
Reviewed-by: WANG Cong <amwang@redhat.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Takao Indoh
2011-07-14 18:05:21 -04:00
committed by Len Brown
parent 1765a367a3
commit 4996c02306
2 changed files with 20 additions and 0 deletions
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5
Documentation/kernel-parameters.txt
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@ -163,6 +163,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
See also Documentation/power/pm.txt, pci=noacpi
acpi_rsdp= [ACPI,EFI,KEXEC]
Pass the RSDP address to the kernel, mostly used
on machines running EFI runtime service to boot the
second kernel for kdump.
acpi_apic_instance= [ACPI, IOAPIC]
Format: <int>
2: use 2nd APIC table, if available