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Commit 4996c023 authored by Takao Indoh's avatar Takao Indoh Committed by Len Brown
Browse files

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: default avatarTakao Indoh <indou.takao@jp.fujitsu.com>
Reviewed-by: default avatarWANG Cong <amwang@redhat.com>
Reviewed-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 1765a367

Documentation/kernel-parameters.txt

+5 −0
Original line number Diff line number Diff line
@@ -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

drivers/acpi/osl.c

+15 −0
Original line number Diff line number Diff line
@@ -237,8 +237,23 @@ void acpi_os_vprintf(const char *fmt, va_list args) 
#endif

}



#ifdef CONFIG_KEXEC

static unsigned long acpi_rsdp;

static int __init setup_acpi_rsdp(char *arg)

{

	acpi_rsdp = simple_strtoul(arg, NULL, 16);

	return 0;

}

early_param("acpi_rsdp", setup_acpi_rsdp);

#endif



acpi_physical_address __init acpi_os_get_root_pointer(void)

{

#ifdef CONFIG_KEXEC

	if (acpi_rsdp)

		return acpi_rsdp;

#endif



	if (efi_enabled) {

		if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)

			return efi.acpi20;