On 08/12/17 08:16, Ingo Molnar wrote: > > * Juergen Gross <jgross@xxxxxxxx> wrote: > >> Xen PVH guests receive the address of the RSDP table from Xen. In order >> to support booting a Xen PVH guest via grub2 using the standard x86 >> boot entry we need a way fro grub2 to pass the RSDP address to the >> kernel. >> >> For this purpose expand the struct setup_header to hold the physical >> address of the RSDP address. Being zero means it isn't specified and >> has to be located the legacy way (searching through low memory or >> EBDA). > > s/fro > /for > > pedantry: > > s/grub2 > /Grub2 Okay. > >> Signed-off-by: Juergen Gross <jgross@xxxxxxxx> >> Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> >> --- >> Documentation/x86/boot.txt | 19 +++++++++++++++++++ >> arch/x86/boot/header.S | 6 +++++- >> arch/x86/include/uapi/asm/bootparam.h | 1 + >> 3 files changed, 25 insertions(+), 1 deletion(-) >> >> diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt >> index 5e9b826b5f62..a33c224797e4 100644 >> --- a/Documentation/x86/boot.txt >> +++ b/Documentation/x86/boot.txt >> @@ -61,6 +61,13 @@ Protocol 2.12: (Kernel 3.8) Added the xloadflags field and extension fields >> to struct boot_params for loading bzImage and ramdisk >> above 4G in 64bit. >> >> +Protocol 2.13: (Kernel 3.14) Support 32- and 64-bit flags being set in >> + xloadflags to support booting a 64 bit kernel from 32 bit >> + EFI > > The changelog should I think declare that we add documentation for the 2.13 > protocol iteration as well. > > Also, please use a consistent spelling of '32-bit' and '64-bit' in the same > sentence! Okay. > >> +Field name: acpi_rsdp_addr >> +Type: write >> +Offset/size: 0x268/8 >> +Protocol: 2.14+ >> + >> + This field can be set by the boot loader to tell the kernel the >> + physical address of the ACPI RSDP table. >> + >> + A value of 0 indicates the kernel should fall back to the standard >> + methods to locate the RSDP (search in EBDA/low memory). > > That's not the only method used: the ACPI RSDP address can also be discovered via > efi.rsdp20 and efi.rsdp, both of which appear to be 32-bit values. Sure, but this is valid for booting via EFI only. > >> **** THE IMAGE CHECKSUM >> >> diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S >> index 850b8762e889..e7184127f309 100644 >> --- a/arch/x86/boot/header.S >> +++ b/arch/x86/boot/header.S >> @@ -300,7 +300,7 @@ _start: >> # Part 2 of the header, from the old setup.S >> >> .ascii "HdrS" # header signature >> - .word 0x020d # header version number (>= 0x0105) >> + .word 0x020e # header version number (>= 0x0105) >> # or else old loadlin-1.5 will fail) >> .globl realmode_swtch >> realmode_swtch: .word 0, 0 # default_switch, SETUPSEG >> @@ -558,6 +558,10 @@ pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr >> init_size: .long INIT_SIZE # kernel initialization size >> handover_offset: .long 0 # Filled in by build.c >> >> +acpi_rsdp_addr: .quad 0 # 64-bit physical pointer to >> + # ACPI RSDP table, added with >> + # version 2.14 > > s/pointer to ACPI RSDP table > /pointer to the ACPI RSDP table Okay. > > Also, a more fundamental question: why doesn't Xen use EFI to hand over hardware > configuration details? I think Jan has answered this question quite well. Juergen -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
