Re: [PATCH v3 2/6] drivers: of: add initialization code for reserved memory

[Grant Likely]

On Tue, 18 Feb 2014 14:37:57 +0100, Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> wrote:
> This patch adds device tree support for contiguous and reserved memory
> regions defined in device tree.
> 
> Large memory blocks can be reliably reserved only during early boot.
> This must happen before the whole memory management subsystem is
> initialized, because we need to ensure that the given contiguous blocks
> are not yet allocated by kernel. Also it must happen before kernel
> mappings for the whole low memory are created, to ensure that there will
> be no mappings (for reserved blocks) or mapping with special properties
> can be created (for CMA blocks). This all happens before device tree
> structures are unflattened, so we need to get reserved memory layout
> directly from fdt.
> 
> Later, those reserved memory regions are assigned to devices on each
> device structure initialization.
> 
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> [joshc: rework to implement new DT binding, provide mechanism for
>  plugging in new reserved-memory node handlers via
>  RESERVEDMEM_OF_DECLARE]
> Signed-off-by: Josh Cartwright <joshc@xxxxxxxxxxxxxx>
> [mszyprow: added generic memory reservation code]
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> ---
>  drivers/of/Kconfig                |    5 +
>  drivers/of/Makefile               |    1 +
>  drivers/of/fdt.c                  |    2 +
>  drivers/of/of_reserved_mem.c      |  390 +++++++++++++++++++++++++++++++++++++
>  drivers/of/platform.c             |    7 +
>  include/asm-generic/vmlinux.lds.h |   11 ++
>  include/linux/of_reserved_mem.h   |   65 +++++++
>  7 files changed, 481 insertions(+)
>  create mode 100644 drivers/of/of_reserved_mem.c
>  create mode 100644 include/linux/of_reserved_mem.h
> 
> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> index c6973f101a3e..f25931dfc6db 100644
> --- a/drivers/of/Kconfig
> +++ b/drivers/of/Kconfig
> @@ -75,4 +75,9 @@ config OF_MTD
>  	depends on MTD
>  	def_bool y
>  
> +config OF_RESERVED_MEM
> +	bool
> +	help
> +	  Helpers to allow for reservation of memory regions
> +
>  endmenu # OF
> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
> index efd05102c405..ed9660adad77 100644
> --- a/drivers/of/Makefile
> +++ b/drivers/of/Makefile
> @@ -9,3 +9,4 @@ obj-$(CONFIG_OF_MDIO)	+= of_mdio.o
>  obj-$(CONFIG_OF_PCI)	+= of_pci.o
>  obj-$(CONFIG_OF_PCI_IRQ)  += of_pci_irq.o
>  obj-$(CONFIG_OF_MTD)	+= of_mtd.o
> +obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o

As mentioned previously, parts of this are absolutely non-optional and
cannot be compiled out. If a region is marked as reserved with this
binding, then the kernel must respect it. That part of the code must be
always configured in.

> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 758b4f8b30b7..c205c84e51a1 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -15,6 +15,7 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_fdt.h>
> +#include <linux/of_reserved_mem.h>
>  #include <linux/string.h>
>  #include <linux/errno.h>
>  #include <linux/slab.h>
> @@ -907,6 +908,7 @@ void __init unflatten_device_tree(void)
>  
>  	/* Get pointer to "/chosen" and "/aliases" nodes for use everywhere */
>  	of_alias_scan(early_init_dt_alloc_memory_arch);
> +	of_reserved_mem_scan();
>  }
>  
>  /**
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> new file mode 100644
> index 000000000000..074d66e41da8
> --- /dev/null
> +++ b/drivers/of/of_reserved_mem.c
> @@ -0,0 +1,390 @@
> +/*
> + * Device tree based initialization code for reserved memory.
> + *
> + * Copyright (c) 2013, The Linux Foundation. All Rights Reserved.
> + * Copyright (c) 2013,2014 Samsung Electronics Co., Ltd.
> + *		http://www.samsung.com
> + * Author: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> + * Author: Josh Cartwright <joshc@xxxxxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of the
> + * License or (at your optional) any later version of the license.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/of.h>
> +#include <linux/of_fdt.h>
> +#include <linux/of_platform.h>
> +#include <linux/mm.h>
> +#include <linux/sizes.h>
> +#include <linux/of_reserved_mem.h>
> +
> +#define MAX_RESERVED_REGIONS	16
> +static struct reserved_mem reserved_mem[MAX_RESERVED_REGIONS];
> +static int reserved_mem_count;
> +
> +#if defined(CONFIG_HAVE_MEMBLOCK)
> +#include <linux/memblock.h>
> +int __init __weak
> +early_init_dt_reserve_memory_arch(phys_addr_t base, phys_addr_t size,
> +				  bool nomap)
> +{
> +	if (memblock_is_region_reserved(base, size))
> +		return -EBUSY;
> +	if (nomap)
> +		return memblock_remove(base, size);
> +	return memblock_reserve(base, size);
> +}
> +
> +int __init __weak
> +early_init_dt_alloc_reserved_memory_arch(phys_addr_t size, phys_addr_t align,
> +					 phys_addr_t start, phys_addr_t end,
> +					 bool nomap, phys_addr_t *res_base)
> +{
> +	/*
> +	 * We use __memblock_alloc_base() since memblock_alloc_base() panic()s.
> +	 */
> +	phys_addr_t base = __memblock_alloc_base(size, align, end);
> +	if (!base)
> +		return -ENOMEM;

Just realized this; this is actually a problem because an allocated
range may end up conflicting with a static range. Reservations must be
done in two passes. First pass should handle static ranges. Second pass
for doing dynamic allocations.

> +
> +	if (base < start) {
> +		memblock_free(base, size);
> +		return -ENOMEM;
> +	}
> +
> +	*res_base = base;
> +	if (nomap)
> +		return memblock_remove(base, size);
> +	return 0;
> +}
> +#else
> +int __init __weak
> +early_init_dt_reserve_memory_arch(phys_addr_t base, phys_addr_t size,
> +				  bool nomap)
> +{
> +	pr_error("Reserved memory not supported, ignoring range 0x%llx - 0x%llx%s\n",
> +		  base, size, nomap ? " (nomap)" : "");
> +	return -ENOSYS;
> +}
> +
> +int __init __weak
> +early_init_dt_alloc_reserved_memory_arch(phys_addr_t size, phys_addr_t align,
> +					 phys_addr_t start, phys_addr_t end,
> +					 bool nomap, phys_addr_t *res_base)
> +{
> +	pr_error("Reserved memory not supported, ignoring region 0x%llx%s\n",
> +		  size, nomap ? " (nomap)" : "");
> +	return -ENOSYS;
> +}
> +#endif
> +
> +/**
> + * res_mem_reserve_reg() - reserve all memory described in 'reg' property
> + */
> +static int __init
> +res_mem_reserve_reg(unsigned long node, const char *uname, int nomap,
> +		    phys_addr_t *res_base, phys_addr_t *res_size)
> +{
> +	int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> +	phys_addr_t base, size;
> +	unsigned long len;
> +	__be32 *prop;
> +
> +	prop = of_get_flat_dt_prop(node, "reg", &len);
> +	if (!prop)
> +		return -ENOENT;
> +
> +	if (len && len % t_len != 0) {
> +		pr_err("Reserved memory: invalid reg property in '%s', skipping node.\n",
> +		       uname);
> +		return -EINVAL;
> +	}
> +
> +	/* store base and size values from the first reg tuple */
> +	*res_base = 0;
> +	while (len > 0) {
> +		base = dt_mem_next_cell(dt_root_addr_cells, &prop);
> +		size = dt_mem_next_cell(dt_root_size_cells, &prop);
> +
> +		if (base && size &&
> +		    early_init_dt_reserve_memory_arch(base, size, nomap) == 0)
> +			pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %ld MiB\n",
> +				uname, &base, (unsigned long)size / SZ_1M);
> +		else
> +			pr_info("Reserved memory: failed to reserve memory for node '%s': base %pa, size %ld MiB\n",
> +				uname, &base, (unsigned long)size / SZ_1M);
> +
> +		len -= t_len;
> +
> +		if (!(*res_base)) {
> +			*res_base = base;
> +			*res_size = size;
> +		}
> +	}
> +	return 0;
> +}
> +
> +/**
> + * res_mem_alloc_size() - allocate reserved memory described by 'size', 'align'
> + *			  and 'alloc-ranges' properties
> + */
> +static int __init
> +res_mem_alloc_size(unsigned long node, const char *uname, int nomap,
> +		   phys_addr_t *res_base, phys_addr_t *res_size)
> +{
> +	int t_len = (dt_root_addr_cells + dt_root_size_cells) * sizeof(__be32);
> +	phys_addr_t start = 0, end = 0;
> +	phys_addr_t base = 0, align = 0, size;
> +	unsigned long len;
> +	__be32 *prop;
> +	int ret;
> +
> +	prop = of_get_flat_dt_prop(node, "size", &len);
> +	if (!prop)
> +		return -EINVAL;
> +
> +	if (len != dt_root_size_cells * sizeof(__be32)) {
> +		pr_err("Reserved memory: invalid size property in '%s' node.\n",
> +				uname);
> +		return -EINVAL;
> +	}
> +	size = dt_mem_next_cell(dt_root_size_cells, &prop);
> +
> +	prop = of_get_flat_dt_prop(node, "align", &len);
> +	if (prop) {
> +		if (len != dt_root_addr_cells * sizeof(__be32)) {
> +			pr_err("Reserved memory: invalid align property in '%s' node.\n",
> +				uname);
> +			return -EINVAL;
> +		}
> +		align = dt_mem_next_cell(dt_root_addr_cells, &prop);
> +	}
> +
> +	prop = of_get_flat_dt_prop(node, "alloc-ranges", &len);
> +	if (prop) {
> +
> +		if (len % t_len != 0) {
> +			pr_err("Reserved memory: invalid alloc-ranges property in '%s', skipping node.\n",
> +			       uname);
> +			return -EINVAL;
> +		}
> +
> +		base = 0;
> +
> +		while (len > 0) {
> +			start = dt_mem_next_cell(dt_root_addr_cells, &prop);
> +			end = start + dt_mem_next_cell(dt_root_size_cells,
> +						       &prop);
> +
> +			ret = early_init_dt_alloc_reserved_memory_arch(size,
> +					align, start, end, nomap, &base);
> +			if (ret == 0) {
> +				pr_debug("Reserved memory: allocated memory for '%s' node: base %pa, size %ld MiB\n",
> +					uname, &base,
> +					(unsigned long)size / SZ_1M);
> +				break;
> +			}
> +			len -= t_len;
> +		}
> +
> +	} else {
> +		ret = early_init_dt_alloc_reserved_memory_arch(size, align,
> +							0, 0, nomap, &base);
> +		if (ret == 0)
> +			pr_debug("Reserved memory: allocated memory for '%s' node: base %pa, size %ld MiB\n",
> +				uname, &base, (unsigned long)size / SZ_1M);
> +	}
> +
> +	if (base == 0) {
> +		pr_info("Reserved memory: failed to allocate memory for node '%s'\n",
> +			uname);
> +		return -ENOMEM;
> +	}
> +
> +	*res_base = base;
> +	*res_size = size;
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id __rmem_of_table_sentinel
> +	__used __section(__reservedmem_of_table_end);
> +
> +/**
> + * res_mem_init_node() - call region specific reserved memory init code
> + */
> +static int __init
> +res_mem_init_node(unsigned long node, const char *uname, phys_addr_t base,
> +		  phys_addr_t size)
> +{
> +	struct reserved_mem *rmem = &reserved_mem[reserved_mem_count];
> +	extern const struct of_device_id __reservedmem_of_table[];
> +	const struct of_device_id *i;
> +
> +	if (reserved_mem_count == ARRAY_SIZE(reserved_mem)) {
> +		pr_err("Reserved memory: not enough space all defined regions.\n");
> +		return -ENOSPC;
> +	}
> +
> +	rmem->base = base;
> +	rmem->size = size;
> +
> +	for (i = __reservedmem_of_table; i < &__rmem_of_table_sentinel; i++) {
> +		reservedmem_of_init_fn initfn = i->data;
> +		const char *compat = i->compatible;
> +
> +		if (!of_flat_dt_is_compatible(node, compat))
> +			continue;
> +
> +		if (initfn(rmem, node, uname) == 0) {
> +			pr_info("Reserved memory: initialized node %s, compatible id %s\n",
> +				uname, compat);
> +			rmem->name = uname;
> +			reserved_mem_count++;
> +			return 0;
> +		}
> +	}
> +	return -EINVAL;
> +}
> +
> +/**
> + * fdt_scan_reserved_mem() - scan a single FDT node for reserved memory
> + */
> +static int __init
> +fdt_scan_reserved_mem(unsigned long node, const char *uname, int depth,
> +		      void *data)
> +{
> +	phys_addr_t base, size;
> +	const char *status;
> +	int nomap;
> +	int err;
> +
> +	status = of_get_flat_dt_prop(node, "status", NULL);
> +	if (status && strcmp(status, "okay") != 0 && strcmp(status, "ok") != 0)
> +		return 0;
> +
> +	nomap = of_get_flat_dt_prop(node, "no-map", NULL) != NULL;
> +
> +	err = res_mem_reserve_reg(node, uname, nomap, &base, &size);
> +	if (err == -ENOENT)
> +		err = res_mem_alloc_size(node, uname, nomap, &base, &size);
> +	if (err)
> +		goto end;
> +
> +	res_mem_init_node(node, uname, base, size);
> +end:
> +	/* scan next node */
> +	return 0;
> +}
> +
> +/**
> + * early_init_dt_scan_reserved_mem() - create reserved memory regions
> + *
> + * This function grabs memory from early allocator for device exclusive use
> + * defined in device tree structures. It should be called by arch specific code
> + * once the early allocator (i.e. memblock) has been fully activated.
> + */
> +void __init early_init_dt_scan_reserved_mem(void)
> +{
> +	of_scan_flat_dt_by_path("/reserved-memory", fdt_scan_reserved_mem,
> +				NULL);
> +}

Just about everything above this point must be moved to fdt.c. Processing the
static reserved regions must be non-optional code. You can factor out
the table of reserved regions if you like, but I want the core
functionality directly in fdt.c.

The dynamic allocation code can be optional, but that is because it
describes dynamic regions that have no possibility of hardware already
using them.

> +
> +/**
> + * of_reserved_mem_scan() - scan and create structures required by reserved
> + *			    memory regions
> + *
> + * This function creates all structures required by reserved memory regions
> + * management code. It should be called by common code once the device tree
> + * has been unflattened.
> + */
> +void __init of_reserved_mem_scan(void)
> +{
> +	struct device_node *root, *np;
> +
> +	root = of_find_node_by_path("/reserved-memory");
> +
> +	if (of_n_addr_cells(root) != dt_root_addr_cells ||
> +	    of_n_size_cells(root) != dt_root_size_cells)
> +		panic("Unsupported address or size cells for /reserved-memory node\n");
> +
> +	for (np = NULL;;) {
> +		const char *name;
> +		int i;
> +
> +		np = of_get_next_available_child(root, np);
> +		if (!np)
> +			break;
> +
> +		name = kbasename(np->full_name);
> +		for (i = 0; i < reserved_mem_count; i++)
> +			if (strcmp(name, reserved_mem[i].name) == 0)
> +				reserved_mem[i].node = np;

I've already commented on the above. kbasename is not a safe match.

> +	}
> +}
> +
> +static inline struct reserved_mem *find_rmem(struct device_node *phandle)
> +{
> +	unsigned int i;
> +	for (i = 0; i < reserved_mem_count; i++)
> +		if (reserved_mem[i].node == phandle)
> +			return &reserved_mem[i];
> +	return NULL;
> +}
> +
> +/**
> + * of_reserved_mem_device_init() - assign reserved memory region to given device
> + *
> + * This function assign memory region pointed by "memory-region" device tree
> + * property to the given device.
> + */
> +void of_reserved_mem_device_init(struct device *dev)
> +{
> +	struct device_node *np = dev->of_node;
> +	struct reserved_mem *rmem;
> +	struct of_phandle_args s;
> +	unsigned int i;
> +
> +	for (i = 0; of_parse_phandle_with_args(np, "memory-region",
> +				"#memory-region-cells", i, &s) == 0; i++) {
> +
> +		rmem = find_rmem(s.np);
> +		if (!rmem || !rmem->ops || !rmem->ops->device_init) {
> +			of_node_put(s.np);
> +			continue;
> +		}
> +
> +		rmem->ops->device_init(rmem, dev, &s);
> +		dev_info(dev, "assigned reserved memory node %s\n",
> +			 rmem->name);
> +		of_node_put(s.np);
> +		break;
> +	}
> +}
> +
> +/**
> + * of_reserved_mem_device_release() - release reserved memory device structures
> + *
> + * This function releases structures allocated for memory region handling for
> + * the given device.
> + */
> +void of_reserved_mem_device_release(struct device *dev)
> +{
> +	struct device_node *np = dev->of_node;
> +	struct reserved_mem *rmem;
> +	struct of_phandle_args s;
> +	unsigned int i;
> +
> +	for (i = 0; of_parse_phandle_with_args(np, "memory-region",
> +				"#memory-region-cells", i, &s) == 0; i++) {
> +
> +		rmem = find_rmem(s.np);
> +		if (rmem && rmem->ops && rmem->ops->device_release)
> +			rmem->ops->device_release(rmem, dev);
> +
> +		of_node_put(s.np);
> +	}
> +}
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 404d1daebefa..3df0b1826e8b 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -21,6 +21,7 @@
>  #include <linux/of_device.h>
>  #include <linux/of_irq.h>
>  #include <linux/of_platform.h>
> +#include <linux/of_reserved_mem.h>
>  #include <linux/platform_device.h>
>  
>  const struct of_device_id of_default_bus_match_table[] = {
> @@ -220,6 +221,8 @@ static struct platform_device *of_platform_device_create_pdata(
>  	dev->dev.bus = &platform_bus_type;
>  	dev->dev.platform_data = platform_data;
>  
> +	of_reserved_mem_device_init(&dev->dev);
> +
>  	/* We do not fill the DMA ops for platform devices by default.
>  	 * This is currently the responsibility of the platform code
>  	 * to do such, possibly using a device notifier
> @@ -227,6 +230,7 @@ static struct platform_device *of_platform_device_create_pdata(
>  
>  	if (of_device_add(dev) != 0) {
>  		platform_device_put(dev);
> +		of_reserved_mem_device_release(&dev->dev);
>  		return NULL;
>  	}
>  
> @@ -282,6 +286,8 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
>  	else
>  		of_device_make_bus_id(&dev->dev);
>  
> +	of_reserved_mem_device_init(&dev->dev);
> +
>  	/* Allow the HW Peripheral ID to be overridden */
>  	prop = of_get_property(node, "arm,primecell-periphid", NULL);
>  	if (prop)
> @@ -308,6 +314,7 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
>  	return dev;
>  
>  err_free:
> +	of_reserved_mem_device_release(&dev->dev);
>  	amba_device_put(dev);
>  	return NULL;
>  }
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index bc2121fa9132..f10f64fcc815 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -167,6 +167,16 @@
>  #define CLK_OF_TABLES()
>  #endif
>  
> +#ifdef CONFIG_OF_RESERVED_MEM
> +#define RESERVEDMEM_OF_TABLES()				\
> +	. = ALIGN(8);					\
> +	VMLINUX_SYMBOL(__reservedmem_of_table) = .;	\
> +	*(__reservedmem_of_table)			\
> +	*(__reservedmem_of_table_end)
> +#else
> +#define RESERVEDMEM_OF_TABLES()
> +#endif
> +
>  #define KERNEL_DTB()							\
>  	STRUCT_ALIGN();							\
>  	VMLINUX_SYMBOL(__dtb_start) = .;				\
> @@ -490,6 +500,7 @@
>  	TRACE_SYSCALLS()						\
>  	MEM_DISCARD(init.rodata)					\
>  	CLK_OF_TABLES()							\
> +	RESERVEDMEM_OF_TABLES()						\
>  	CLKSRC_OF_TABLES()						\
>  	KERNEL_DTB()							\
>  	IRQCHIP_OF_MATCH_TABLE()
> diff --git a/include/linux/of_reserved_mem.h b/include/linux/of_reserved_mem.h
> new file mode 100644
> index 000000000000..39a4fb17a5ea
> --- /dev/null
> +++ b/include/linux/of_reserved_mem.h
> @@ -0,0 +1,65 @@
> +#ifndef __OF_RESERVED_MEM_H
> +#define __OF_RESERVED_MEM_H
> +
> +struct cma;
> +struct platform_device;
> +struct of_phandle_args;
> +struct reserved_mem_ops;
> +
> +struct reserved_mem {
> +	const char			*name;
> +	struct device_node		*node;
> +	const struct reserved_mem_ops	*ops;
> +	phys_addr_t			base;
> +	phys_addr_t			size;
> +	void				*priv;
> +};
> +
> +struct reserved_mem_ops {
> +	void	(*device_init)(struct reserved_mem *rmem,
> +			       struct device *dev,
> +			       struct of_phandle_args *args);
> +	void	(*device_release)(struct reserved_mem *rmem,
> +				  struct device *dev);
> +};
> +
> +typedef int (*reservedmem_of_init_fn)(struct reserved_mem *rmem,
> +				      unsigned long node, const char *uname);
> +
> +#ifdef CONFIG_OF_RESERVED_MEM
> +void of_reserved_mem_device_init(struct device *dev);
> +void of_reserved_mem_device_release(struct device *dev);
> +void early_init_dt_scan_reserved_mem(void);
> +void of_reserved_mem_scan(void);
> +
> +int of_parse_flat_dt_reg(unsigned long node, const char *uname,
> +			 phys_addr_t *base, phys_addr_t *size);
> +int of_parse_flat_dt_size(unsigned long node, const char *uname,
> +			  phys_addr_t *size);
> +
> +#define RESERVEDMEM_OF_DECLARE(name, compat, init)			\
> +	static const struct of_device_id __reservedmem_of_table_##name	\
> +		__used __section(__reservedmem_of_table)		\
> +		 = { .compatible = compat,				\
> +		     .data = (init == (reservedmem_of_init_fn)NULL) ?	\
> +				init : init }
> +
> +#else
> +static inline void of_reserved_mem_device_init(struct device *dev) { }
> +
> +static inline
> +void of_reserved_mem_device_release(struct device *pdev) { }
> +
> +static inline void early_init_dt_scan_reserved_mem(void) { }
> +static inline void of_reserved_mem_scan(void) { }
> +
> +#define RESERVEDMEM_OF_DECLARE(name, compat, init)			\
> +	static const struct of_device_id __reservedmem_of_table_##name	\
> +		__attribute__((unused))					\
> +		 = { .compatible = compat,				\
> +		     .data = (init == (reservedmem_of_init_fn)NULL) ?	\
> +				init : init }
> +
> +#endif
> +
> +#endif /* __OF_RESERVED_MEM_H */
> -- 
> 1.7.9.5
> 

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