sched: rt-group: clean up the ifdeffery

[linux-2.6-omap-h63xx.git] / Documentation / i386 / boot.txt

diff --git a/Documentation/i386/boot.txt b/Documentation/i386/boot.txt
index 2f75e750e4f5c650a89df593ead1a1ff320eee62..fc49b79bc1ab3341b16fe19ea49402f9fd1955e2 100644 (file)
--- a/Documentation/i386/boot.txt
+++ b/Documentation/i386/boot.txt
@@ -785,3 +785,41 @@ IMPORTANT: All the hooks are required to preserve %esp, %ebp, %esi and
        After completing your hook, you should jump to the address
        that was in this field before your boot loader overwrote it
        (relocated, if appropriate.)
        After completing your hook, you should jump to the address
        that was in this field before your boot loader overwrote it
        (relocated, if appropriate.)

+
+
+**** 32-bit BOOT PROTOCOL
+
+For machine with some new BIOS other than legacy BIOS, such as EFI,
+LinuxBIOS, etc, and kexec, the 16-bit real mode setup code in kernel
+based on legacy BIOS can not be used, so a 32-bit boot protocol needs
+to be defined.
+
+In 32-bit boot protocol, the first step in loading a Linux kernel
+should be to setup the boot parameters (struct boot_params,
+traditionally known as "zero page"). The memory for struct boot_params
+should be allocated and initialized to all zero. Then the setup header
+from offset 0x01f1 of kernel image on should be loaded into struct
+boot_params and examined. The end of setup header can be calculated as
+follow:
+
+       0x0202 + byte value at offset 0x0201
+
+In addition to read/modify/write the setup header of the struct
+boot_params as that of 16-bit boot protocol, the boot loader should
+also fill the additional fields of the struct boot_params as that
+described in zero-page.txt.
+
+After setupping the struct boot_params, the boot loader can load the
+32/64-bit kernel in the same way as that of 16-bit boot protocol.
+
+In 32-bit boot protocol, the kernel is started by jumping to the
+32-bit kernel entry point, which is the start address of loaded
+32/64-bit kernel.
+
+At entry, the CPU must be in 32-bit protected mode with paging
+disabled; a GDT must be loaded with the descriptors for selectors
+__BOOT_CS(0x10) and __BOOT_DS(0x18); both descriptors must be 4G flat
+segment; __BOOS_CS must have execute/read permission, and __BOOT_DS
+must have read/write permission; CS must be __BOOT_CS and DS, ES, SS
+must be __BOOT_DS; interrupt must be disabled; %esi must hold the base
+address of the struct boot_params; %ebp, %edi and %ebx must be zero.