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authorTakao Indoh <indou.takao@jp.fujitsu.com>2011-07-14 18:05:21 -0400
committerLen Brown <len.brown@intel.com>2011-07-16 18:40:16 -0400
commit4996c02306a25def1d352ec8e8f48895bbc7dea9 (patch)
tree924944ad2dc7fd456e6ce6c097e552bfebacabf6 /Documentation/kernel-parameters.txt
parent1765a367a3b5d5e9692949b0c5ec933eff2c0701 (diff)
downloadlinux-rt-4996c02306a25def1d352ec8e8f48895bbc7dea9.tar.gz
ACPI: introduce "acpi_rsdp=" parameter for kdump
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>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt5
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index aa47be71df4c..37713bcf7778 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -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