149 lines
7.3 KiB
Text
149 lines
7.3 KiB
Text
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19 Platform limitations
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***********************
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GRUB2 is designed to be portable and is actually ported across
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platforms. We try to keep all platforms at the level. Unfortunately
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some platforms are better supported than others. This is detailed in
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current and 2 following sections.
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ARC platform is unable to change datetime (firmware doesn't seem to
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provide a function for it). EMU has similar limitation.
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On EMU platform no serial port is available.
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Console charset refers only to firmware-assisted console. gfxterm is
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always Unicode (see Internationalisation section for its limitations).
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Serial is configurable to UTF-8 or ASCII (see Internationalisation). In
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case of qemu and coreboot ports the refered console is vga_text.
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Loongson always uses gfxterm.
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Most limited one is ASCII. CP437 provides additionally
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pseudographics. GRUB2 doesn't use any language characters from CP437 as
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often CP437 is replaced by national encoding compatible only in
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pseudographics. Unicode is the most versatile charset which supports
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many languages. However the actual console may be much more limited
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depending on firmware
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On BIOS network is supported only if the image is loaded through
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network. On sparc64 GRUB is unable to determine which server it was
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booted from.
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Direct ATA/AHCI support allows to circumvent various firmware
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limitations but isn't needed for normal operation except on baremetal
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ports.
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AT keyboard support allows keyboard layout remapping and support for
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keys not available through firmware. It isn't needed for normal
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operation except baremetal ports.
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Speaker allows morse and spkmodem communication.
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USB support provides benefits similar to ATA (for USB disks) or AT
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(for USB keyboards). In addition it allows USBserial.
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Chainloading refers to the ability to load another bootloader through
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the same protocol
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Hints allow faster disk discovery by already knowing in advance which
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is the disk in question. On some platforms hints are correct unless you
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move the disk between boots. On other platforms it's just an educated
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guess. Note that hint failure results in just reduced performance, not
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a failure
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BadRAM is the ability to mark some of the RAM as "bad". Note: due to
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protocol limitations mips-loongson (with Linux protocol) and
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mips-qemu_mips can use only memory up to first hole.
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Bootlocation is ability of GRUB to automatically detect where it
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boots from. "disk" means the detection is limited to detecting the disk
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with partition being discovered on install time. "partition" means that
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disk and partiton can be automatically discovered. "file" means that
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boot image file name as well as disk and partition can be discovered.
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For consistency default install ignores partition and relies solely on
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disk detection. If no bootlocation discovery is available or boot and
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grub-root disks are different, UUID is used instead. On ARC if no
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device to install to is specified, UUID is used instead as well.
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BIOS Coreboot Multiboot Qemu
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video yes yes yes yes
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console CP437 CP437 CP437 CP437
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charset
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network yes (*) no no no
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ATA/AHCI yes yes yes yes
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AT keyboard yes yes yes yes
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Speaker yes yes yes yes
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USB yes yes yes yes
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chainloader local yes yes no
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cpuid partial partial partial partial
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rdmsr partial partial partial partial
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wrmsr partial partial partial partial
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hints guess guess guess guess
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PCI yes yes yes yes
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badram yes yes yes yes
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compression always pointless no no
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exit yes no no no
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bootlocation disk no no no
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ia32 EFI amd64 EFI ia32 Itanium
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IEEE1275
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video yes yes no no
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console Unicode Unicode ASCII Unicode
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charset
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network yes yes yes yes
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ATA/AHCI yes yes yes no
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AT keyboard yes yes yes no
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Speaker yes yes yes no
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USB yes yes yes no
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chainloader local local no local
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cpuid partial partial partial no
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rdmsr partial partial partial no
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wrmsr partial partial partial no
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hints guess guess good guess
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PCI yes yes yes no
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badram yes yes no yes
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compression no no no no
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exit yes yes yes yes
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bootlocation file file file, file
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ignored
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Loongson sparc64 Powerpc ARC
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video yes no yes no
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console N/A ASCII ASCII ASCII
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charset
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network no yes (*) yes no
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ATA/AHCI yes no no no
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AT keyboard yes no no no
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Speaker no no no no
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USB yes no no no
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chainloader yes no no no
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cpuid no no no no
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rdmsr no no no no
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wrmsr no no no no
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hints good good good no
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PCI yes no no no
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badram yes (*) no no no
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compression configurable no no configurable
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exit no yes yes yes
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bootlocation no partition file file (*)
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MIPS qemu emu xen
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video no yes no
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console CP437 Unicode (*) ASCII
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charset
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network no yes no
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ATA/AHCI yes no no
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AT keyboard yes no no
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Speaker no no no
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USB N/A yes no
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chainloader yes no yes
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cpuid no no yes
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rdmsr no no yes
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wrmsr no no yes
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hints guess no no
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PCI no no no
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badram yes (*) no no
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compression configurable no no
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exit no yes no
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bootlocation no file no
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