From 968de4f02621db35b8ae5239c8cfc6664fb872d8 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" <ebiederm@xmission.com> Date: Thu, 7 Dec 2006 02:14:04 +0100 Subject: [PATCH] i386: Relocatable kernel support This patch modifies the i386 kernel so that if CONFIG_RELOCATABLE is selected it will be able to be loaded at any 4K aligned address below 1G. The technique used is to compile the decompressor with -fPIC and modify it so the decompressor is fully relocatable. For the main kernel relocations are generated. Resulting in a kernel that is relocatable with no runtime overhead and no need to modify the source code. A reserved 32bit word in the parameters has been assigned to serve as a stack so we figure out where are running. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> --- arch/i386/boot/setup.S | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-) (limited to 'arch/i386/boot/setup.S') diff --git a/arch/i386/boot/setup.S b/arch/i386/boot/setup.S index 3aec4538..9aa8b05 100644 --- a/arch/i386/boot/setup.S +++ b/arch/i386/boot/setup.S @@ -588,11 +588,6 @@ rmodeswtch_normal: call default_switch rmodeswtch_end: -# we get the code32 start address and modify the below 'jmpi' -# (loader may have changed it) - movl %cs:code32_start, %eax - movl %eax, %cs:code32 - # Now we move the system to its rightful place ... but we check if we have a # big-kernel. In that case we *must* not move it ... testb $LOADED_HIGH, %cs:loadflags @@ -788,11 +783,12 @@ a20_err_msg: a20_done: #endif /* CONFIG_X86_VOYAGER */ -# set up gdt and idt +# set up gdt and idt and 32bit start address lidt idt_48 # load idt with 0,0 xorl %eax, %eax # Compute gdt_base movw %ds, %ax # (Convert %ds:gdt to a linear ptr) shll $4, %eax + addl %eax, code32 addl $gdt, %eax movl %eax, (gdt_48+2) lgdt gdt_48 # load gdt with whatever is @@ -851,9 +847,26 @@ flush_instr: # Manual, Mixing 16-bit and 32-bit code, page 16-6) .byte 0x66, 0xea # prefix + jmpi-opcode -code32: .long 0x1000 # will be set to 0x100000 - # for big kernels +code32: .long startup_32 # will be set to %cs+startup_32 .word __BOOT_CS +.code32 +startup_32: + movl $(__BOOT_DS), %eax + movl %eax, %ds + movl %eax, %es + movl %eax, %fs + movl %eax, %gs + movl %eax, %ss + + xorl %eax, %eax +1: incl %eax # check that A20 really IS enabled + movl %eax, 0x00000000 # loop forever if it isn't + cmpl %eax, 0x00100000 + je 1b + + # Jump to the 32bit entry point + jmpl *(code32_start - start + (DELTA_INITSEG << 4))(%esi) +.code16 # Here's a bunch of information about your current kernel.. kernel_version: .ascii UTS_RELEASE -- cgit v1.1 From be274eeaf20b4c7155242645d5e2c48b023e609b Mon Sep 17 00:00:00 2001 From: Vivek Goyal <vgoyal@in.ibm.com> Date: Thu, 7 Dec 2006 02:14:04 +0100 Subject: [PATCH] i386: extend bzImage protocol for relocatable protected mode kernel Extend bzImage protocol to enable bootloaders to load a completely relocatable bzImage. Now protected mode component of kernel is also relocatable and a boot-loader can load the protected mode component at a differnt physical address than 1MB. (If kernel was built with CONFIG_RELOCATABLE) Kexec can make use of it to load this kernel at a different physical address to capture kernel crash dumps. Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> --- arch/i386/boot/setup.S | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'arch/i386/boot/setup.S') diff --git a/arch/i386/boot/setup.S b/arch/i386/boot/setup.S index 9aa8b05..06edf1c 100644 --- a/arch/i386/boot/setup.S +++ b/arch/i386/boot/setup.S @@ -81,7 +81,7 @@ start: # This is the setup header, and it must start at %cs:2 (old 0x9020:2) .ascii "HdrS" # header signature - .word 0x0204 # header version number (>= 0x0105) + .word 0x0205 # header version number (>= 0x0105) # or else old loadlin-1.5 will fail) realmode_swtch: .word 0, 0 # default_switch, SETUPSEG start_sys_seg: .word SYSSEG @@ -160,6 +160,17 @@ ramdisk_max: .long (-__PAGE_OFFSET-(512 << 20)-1) & 0x7fffffff # The highest safe address for # the contents of an initrd +kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment + #required for protected mode + #kernel +#ifdef CONFIG_RELOCATABLE +relocatable_kernel: .byte 1 +#else +relocatable_kernel: .byte 0 +#endif +pad2: .byte 0 +pad3: .word 0 + trampoline: call start_of_setup .align 16 # The offset at this point is 0x240 -- cgit v1.1