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Commit 37dd2bad authored by Kumar Gala's avatar Kumar Gala Committed by Paul Mackerras
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[POWERPC] 85xx: Add support for relocatable kernel (and booting at non-zero) 



Added support to allow an 85xx kernel to be run from a non-zero physical
address (useful for cooperative asymmetric multiprocessing situations and
kdump).  The support can be configured at compile time by setting
CONFIG_PAGE_OFFSET, CONFIG_KERNEL_START, and CONFIG_PHYSICAL_START as
desired.

Alternatively, the kernel build can set CONFIG_RELOCATABLE.  Setting this
config option causes the kernel to determine at runtime the physical
addresses of CONFIG_PAGE_OFFSET and CONFIG_KERNEL_START.  If
CONFIG_RELOCATABLE is set, then CONFIG_PHYSICAL_START has no meaning.
However, CONFIG_PHYSICAL_START will always be used to set the LOAD program
header physical address field in the resulting ELF image.

Currently we are limited to running at a physical address that is a
multiple of 256M.  This is due to how we map TLBs to cover
lowmem.  This should be fixed to allow 64M or maybe even 16M alignment
in the future.  It is considered an error to try and run a kernel at a
non-aligned physical address.

All the magic for this support is accomplished by proper initialization
of the kernel memory subsystem and use of ARCH_PFN_OFFSET.

The use of ARCH_PFN_OFFSET only affects normal memory and not IO mappings.
ioremap uses map_page and isn't affected by ARCH_PFN_OFFSET.

/dev/mem continues to allow access to any physical address in the system
regardless of how CONFIG_PHYSICAL_START is set.

Signed-off-by: default avatarKumar Gala <galak@kernel.crashing.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 96f1bb8a

arch/powerpc/Kconfig

+66 −3
Original line number Diff line number Diff line
@@ -656,21 +656,76 @@ config LOWMEM_SIZE 
	hex "Maximum low memory size (in bytes)" if LOWMEM_SIZE_BOOL

	default "0x30000000"



config RELOCATABLE

	bool "Build a relocatable kernel (EXPERIMENTAL)"

	depends on EXPERIMENTAL && ADVANCED_OPTIONS && FLATMEM && FSL_BOOKE

	help

	  This builds a kernel image that is capable of running at the

	  location the kernel is loaded at (some alignment restrictions may

	  exist).



	  One use is for the kexec on panic case where the recovery kernel

	  must live at a different physical address than the primary

	  kernel.



	  Note: If CONFIG_RELOCATABLE=y, then the kernel runs from the address

	  it has been loaded at and the compile time physical addresses

	  CONFIG_PHYSICAL_START is ignored.  However CONFIG_PHYSICAL_START

	  setting can still be useful to bootwrappers that need to know the

	  load location of the kernel (eg. u-boot/mkimage).



config PAGE_OFFSET_BOOL

	bool "Set custom page offset address"

	depends on ADVANCED_OPTIONS

	help

	  This option allows you to set the kernel virtual address at which

	  the kernel will map low memory.  This can be useful in optimizing

	  the virtual memory layout of the system.



	  Say N here unless you know what you are doing.



config PAGE_OFFSET

	hex "Virtual address of memory base" if PAGE_OFFSET_BOOL

	default "0xc0000000"



config KERNEL_START_BOOL

	bool "Set custom kernel base address"

	depends on ADVANCED_OPTIONS

	help

	  This option allows you to set the kernel virtual address at which

	  the kernel will map low memory (the kernel image will be linked at

	  this address).  This can be useful in optimizing the virtual memory

	  layout of the system.

	  the kernel will be loaded.  Normally this should match PAGE_OFFSET

	  however there are times (like kdump) that one might not want them

	  to be the same.



	  Say N here unless you know what you are doing.



config KERNEL_START

	hex "Virtual address of kernel base" if KERNEL_START_BOOL

	default PAGE_OFFSET if PAGE_OFFSET_BOOL

	default "0xc2000000" if CRASH_DUMP

	default "0xc0000000"



config PHYSICAL_START_BOOL

	bool "Set physical address where the kernel is loaded"

	depends on ADVANCED_OPTIONS && FLATMEM && FSL_BOOKE

	help

	  This gives the physical address where the kernel is loaded.



	  Say N here unless you know what you are doing.



config PHYSICAL_START

	hex "Physical address where the kernel is loaded" if PHYSICAL_START_BOOL

	default "0x02000000" if PPC_STD_MMU && CRASH_DUMP

	default "0x00000000"



config PHYSICAL_ALIGN

	hex

	default "0x10000000" if FSL_BOOKE

	help

	  This value puts the alignment restrictions on physical address

	  where kernel is loaded and run from. Kernel is compiled for an

	  address which meets above alignment restriction.



config TASK_SIZE_BOOL

	bool "Set custom user task size"

	depends on ADVANCED_OPTIONS
@@ -717,9 +772,17 @@ config PIN_TLB 
endmenu



if PPC64

config PAGE_OFFSET

	hex

	default "0xc000000000000000"

config KERNEL_START

	hex

	default "0xc000000002000000" if CRASH_DUMP

	default "0xc000000000000000"

config PHYSICAL_START

	hex

	default "0x02000000" if CRASH_DUMP

	default "0x00000000"

endif



source "net/Kconfig"

arch/powerpc/kernel/head_fsl_booke.S

+11 −0
Original line number Diff line number Diff line
@@ -371,6 +371,17 @@ skpinv: addi r6,r6,1 /* Increment */ 


	bl	early_init



#ifdef CONFIG_RELOCATABLE

	lis	r3,kernstart_addr@ha

	la	r3,kernstart_addr@l(r3)

#ifdef CONFIG_PHYS_64BIT

	stw	r23,0(r3)

	stw	r25,4(r3)

#else

	stw	r25,0(r3)

#endif

#endif



	mfspr	r3,SPRN_TLB1CFG

	andi.	r3,r3,0xfff

	lis	r4,num_tlbcam_entries@ha

arch/powerpc/kernel/prom.c

+4 −0
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ 
#include <asm/pci-bridge.h>

#include <asm/phyp_dump.h>

#include <asm/kexec.h>

#include <mm/mmu_decl.h>



#ifdef DEBUG

#define DBG(fmt...) printk(KERN_ERR fmt)
@@ -978,7 +979,10 @@ static int __init early_init_dt_scan_memory(unsigned long node, 
		}

#endif

		lmb_add(base, size);



		memstart_addr = min((u64)memstart_addr, base);

	}



	return 0;

}

arch/powerpc/kernel/setup_64.c

+1 −1
Original line number Diff line number Diff line
@@ -435,7 +435,7 @@ void __init setup_system(void) 
		printk("htab_address                  = 0x%p\n", htab_address);

	printk("htab_hash_mask                = 0x%lx\n", htab_hash_mask);

#if PHYSICAL_START > 0

	printk("physical_start                = 0x%x\n", PHYSICAL_START);

	printk("physical_start                = 0x%lx\n", PHYSICAL_START);

#endif

	printk("-----------------------------------------------------\n");

arch/powerpc/mm/fsl_booke_mmu.c

+1 −1
Original line number Diff line number Diff line
@@ -202,7 +202,7 @@ adjust_total_lowmem(void) 
		cam_max_size = max_lowmem_size;



	/* adjust lowmem size to max_lowmem_size */

	ram = min(max_lowmem_size, total_lowmem);

	ram = min(max_lowmem_size, (phys_addr_t)total_lowmem);



	/* Calculate CAM values */

	__cam0 = 1UL << 2 * (__ilog2(ram) / 2);