Add reloc keyworkd to let EFI bootstrap load amd64 kernel at any address

EFI bootstrap assumes it can copy the amd64 kernel to its ELF load
address (that is KERNTEXTOFF - KERNBASE = 0x200000), but it can
clash with previous UEFI memory allocation, as described here:
http://mail-index.netbsd.org/tech-kern/2023/04/07/msg028833.html

This change adds a reloc keyword for controling where the EFI
boostrap will copy the kernel image. Possible values are:
default - the default and prior behavior, copy at 0x200000.
none - do not copy and use the kernel image where it was loaded.
address - specify an explicit address where to copy the kernel.

This comes with an amd64 kernel patch that makes it self-relocatable.
It first discover where it was loaded in memory, and if this is
different than the expected 0x200000, hhe the kernel relocates
itself and start over at the right address.

Remove banner printing code from bootloaders, add it to libsa.

This harmonizes efiboot and the various x86 bootloaders to use shared
code for printing the banner. By friendly coincidence, it also adds
support for specifying 'banner=' in arm efiboot's boot.cfg, as on x86.

Add multiboot 2 support to x86 bootloaders

multiboot 2 is required to boot Xen on an EFI system.
This also require a kernel patch for properly discovering
the ACPI RSDP, which is available after 20190912, in
src/sys/arch/x86/acpi/acpi_machdep.c 1.26-1.28

There are a few missing bit in this multiboot 2 implementation
(which are unused by Xen):
- Header tags Address, Freambuffer, and Relocatable are ignored
- Tags APM and Network are not provided
- Tags ACPI old and ACP new are only provided for ACPI boot
- Tag boot device does not provides the subpart (BSD disklabel partition)

Notes:
- multiboot2 is disabled in dosboot, otherwise the binary
gets too big and build fails.
- in src/sys/arch/i386/stand/efiboot, consinit() is renamed
as efi_consinit() to avoid prototype conflicts in src/sys/sys/systm.h

branches: 1.9.2;
Added BTINFO_EFIMEMMAP compaction support to x86 efiboot.

branches: 1.8.2;
efiboot: Added network boot support.

efiboot: Added serial console support.

efiboot: system can boot from CD/DVD-ROM media.

branches: 1.5.2; 1.5.8; 1.5.10;
efiboot: implement consdev command.

no support to change console device for efiboot yet.
only pass console parameters to kernel.

branches: 1.4.2; 1.4.6; 1.4.8;
PR/51953: fix unable to boot on some AMD machine.

Delayed the timing to copy the kernel to actual address.
copy routine from common/lib/libc/arch/x86_64/string/bcopy.S

efiboot: don't call WaitForSingleEvent after ExitBootServices is called.

efiboot: pass memory map after ExitBootService is called to kernel.

branches: 1.1.2;
Initial commit of native amd64 EFI boot loader.

Remove banner printing code from bootloaders, add it to libsa.

This harmonizes efiboot and the various x86 bootloaders to use shared
code for printing the banner. By friendly coincidence, it also adds
support for specifying 'banner=' in arm efiboot's boot.cfg, as on x86.

Add multiboot 2 support to x86 bootloaders

multiboot 2 is required to boot Xen on an EFI system.
This also require a kernel patch for properly discovering
the ACPI RSDP, which is available after 20190912, in
src/sys/arch/x86/acpi/acpi_machdep.c 1.26-1.28

There are a few missing bit in this multiboot 2 implementation
(which are unused by Xen):
- Header tags Address, Freambuffer, and Relocatable are ignored
- Tags APM and Network are not provided
- Tags ACPI old and ACP new are only provided for ACPI boot
- Tag boot device does not provides the subpart (BSD disklabel partition)

Notes:
- multiboot2 is disabled in dosboot, otherwise the binary
gets too big and build fails.
- in src/sys/arch/i386/stand/efiboot, consinit() is renamed
as efi_consinit() to avoid prototype conflicts in src/sys/sys/systm.h

branches: 1.9.2;
Added BTINFO_EFIMEMMAP compaction support to x86 efiboot.

branches: 1.8.2;
efiboot: Added network boot support.

efiboot: Added serial console support.

efiboot: system can boot from CD/DVD-ROM media.

branches: 1.5.2; 1.5.8; 1.5.10;
efiboot: implement consdev command.

no support to change console device for efiboot yet.
only pass console parameters to kernel.

branches: 1.4.2; 1.4.6; 1.4.8;
PR/51953: fix unable to boot on some AMD machine.

Delayed the timing to copy the kernel to actual address.
copy routine from common/lib/libc/arch/x86_64/string/bcopy.S

efiboot: don't call WaitForSingleEvent after ExitBootServices is called.

efiboot: pass memory map after ExitBootService is called to kernel.

branches: 1.1.2;
Initial commit of native amd64 EFI boot loader.

Add multiboot 2 support to x86 bootloaders

multiboot 2 is required to boot Xen on an EFI system.
This also require a kernel patch for properly discovering
the ACPI RSDP, which is available after 20190912, in
src/sys/arch/x86/acpi/acpi_machdep.c 1.26-1.28

There are a few missing bit in this multiboot 2 implementation
(which are unused by Xen):
- Header tags Address, Freambuffer, and Relocatable are ignored
- Tags APM and Network are not provided
- Tags ACPI old and ACP new are only provided for ACPI boot
- Tag boot device does not provides the subpart (BSD disklabel partition)

Notes:
- multiboot2 is disabled in dosboot, otherwise the binary
gets too big and build fails.
- in src/sys/arch/i386/stand/efiboot, consinit() is renamed
as efi_consinit() to avoid prototype conflicts in src/sys/sys/systm.h

Added BTINFO_EFIMEMMAP compaction support to x86 efiboot.

efiboot: Added network boot support.

efiboot: Added serial console support.

efiboot: system can boot from CD/DVD-ROM media.

branches: 1.5.2; 1.5.8; 1.5.10;
efiboot: implement consdev command.

no support to change console device for efiboot yet.
only pass console parameters to kernel.

branches: 1.4.2; 1.4.6; 1.4.8;
PR/51953: fix unable to boot on some AMD machine.

Delayed the timing to copy the kernel to actual address.
copy routine from common/lib/libc/arch/x86_64/string/bcopy.S

efiboot: don't call WaitForSingleEvent after ExitBootServices is called.

efiboot: pass memory map after ExitBootService is called to kernel.

branches: 1.1.2;
Initial commit of native amd64 EFI boot loader.

Added BTINFO_EFIMEMMAP compaction support to x86 efiboot.

efiboot: Added network boot support.

efiboot: Added serial console support.

efiboot: system can boot from CD/DVD-ROM media.

branches: 1.5.2; 1.5.8; 1.5.10;
efiboot: implement consdev command.

no support to change console device for efiboot yet.
only pass console parameters to kernel.

branches: 1.4.2; 1.4.6; 1.4.8;
PR/51953: fix unable to boot on some AMD machine.

Delayed the timing to copy the kernel to actual address.
copy routine from common/lib/libc/arch/x86_64/string/bcopy.S

efiboot: don't call WaitForSingleEvent after ExitBootServices is called.

efiboot: pass memory map after ExitBootService is called to kernel.

branches: 1.1.2;
Initial commit of native amd64 EFI boot loader.

efiboot: Added network boot support.

efiboot: Added serial console support.

efiboot: system can boot from CD/DVD-ROM media.

branches: 1.5.2; 1.5.8; 1.5.10;
efiboot: implement consdev command.

no support to change console device for efiboot yet.
only pass console parameters to kernel.

branches: 1.4.2; 1.4.6; 1.4.8;
PR/51953: fix unable to boot on some AMD machine.

Delayed the timing to copy the kernel to actual address.
copy routine from common/lib/libc/arch/x86_64/string/bcopy.S

efiboot: don't call WaitForSingleEvent after ExitBootServices is called.

efiboot: pass memory map after ExitBootService is called to kernel.

branches: 1.1.2;
Initial commit of native amd64 EFI boot loader.

efiboot: implement consdev command.

no support to change console device for efiboot yet.
only pass console parameters to kernel.

branches: 1.4.2; 1.4.8;
PR/51953: fix unable to boot on some AMD machine.

Delayed the timing to copy the kernel to actual address.
copy routine from common/lib/libc/arch/x86_64/string/bcopy.S

efiboot: don't call WaitForSingleEvent after ExitBootServices is called.

efiboot: pass memory map after ExitBootService is called to kernel.

branches: 1.1.2;
Initial commit of native amd64 EFI boot loader.

PR/51953: fix unable to boot on some AMD machine.

Delayed the timing to copy the kernel to actual address.
copy routine from common/lib/libc/arch/x86_64/string/bcopy.S

efiboot: don't call WaitForSingleEvent after ExitBootServices is called.

efiboot: pass memory map after ExitBootService is called to kernel.

branches: 1.1.2;
Initial commit of native amd64 EFI boot loader.

Initial commit of native amd64 EFI boot loader.