ACPI: introduce "acpi_rsdp=" parameter for kdump (4996c023) · Commits · 戴 / test

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>

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;

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