RE: [RFC] fdt:free the fdt reserved memory

[Wang, Yalin]

> -----Original Message-----
> From: Grant Likely [mailto:glikely@xxxxxxxxxxxx] On Behalf Of Grant Likely
> Sent: Wednesday, September 24, 2014 10:45 PM
> To: Wang, Yalin; 'robh+dt@xxxxxxxxxx'; 'devicetree@xxxxxxxxxxxxxxx';
> 'pawel.moll@xxxxxxx'; 'mark.rutland@xxxxxxx';
> 'ijc+devicetree@xxxxxxxxxxxxxx'; 'linux-kernel@xxxxxxxxxxxxxxx'
> Subject: Re: [RFC] fdt:free the fdt reserved memory
> 
> On Thu, 18 Sep 2014 17:25:12 +0800, "Wang, Yalin"
> <Yalin.Wang@xxxxxxxxxxxxxx> wrote:
> > This patch make some change to unflatten_dt_node(), make sure the
> > device_node don't reference to fdt raw blob memory, so that we can
> > free the raw blob reserved memory after initcalls.
> >
> > Signed-off-by: Yalin Wang <yalin.wang@xxxxxxxxxxxxxx>
> 
> Do you have any measurements showing a change in available memory before
> and after the patch?
> 
Does anyone have a look at this patch?
It can save 12K on my platform,
My dtb is 164K

Thanks

> 
> > ---
> >  drivers/of/fdt.c       | 27 +++++++++++++++++++++++----
> >  include/linux/of_fdt.h |  2 ++
> >  2 files changed, 25 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index
> > 79cb831..e891ef6 100644
> > --- a/drivers/of/fdt.c
> > +++ b/drivers/of/fdt.c
> > @@ -240,6 +240,7 @@ static void * unflatten_dt_node(void *blob,
> >  	     (offset = fdt_next_property_offset(blob, offset))) {
> >  		const char *pname;
> >  		u32 sz;
> > +		int name_len;
> >
> >  		if (!(p = fdt_getprop_by_offset(blob, offset, &pname, &sz))) {
> >  			offset = -FDT_ERR_INTERNAL;
> > @@ -250,10 +251,12 @@ static void * unflatten_dt_node(void *blob,
> >  			pr_info("Can't find property name in list !\n");
> >  			break;
> >  		}
> > +		name_len = strlen(pname);
> >  		if (strcmp(pname, "name") == 0)
> >  			has_name = 1;
> > -		pp = unflatten_dt_alloc(&mem, sizeof(struct property),
> > -					__alignof__(struct property));
> > +		pp = unflatten_dt_alloc(&mem,
> > +				ALIGN(sizeof(struct property) + name_len + 1, 4)
> > +				+ sz, __alignof__(struct property));
> >  		if (allnextpp) {
> >  			/* We accept flattened tree phandles either in
> >  			 * ePAPR-style "phandle" properties, or the @@ -270,9
> +273,11 @@
> > static void * unflatten_dt_node(void *blob,
> >  			 * stuff */
> >  			if (strcmp(pname, "ibm,phandle") == 0)
> >  				np->phandle = be32_to_cpup(p);
> > -			pp->name = (char *)pname;
> > +			pp->name = (char *)memcpy(pp + 1, pname, name_len + 1);
> >  			pp->length = sz;
> > -			pp->value = (__be32 *)p;
> > +			pp->value = (__be32 *)memcpy((void *)pp +
> > +					ALIGN(sizeof(struct property) +
> > +						name_len + 1, 4), p, sz);
> >  			*prev_pp = pp;
> >  			prev_pp = &pp->next;
> >  		}
> > @@ -564,6 +569,20 @@ void __init early_init_fdt_scan_reserved_mem(void)
> >  	fdt_init_reserved_mem();
> >  }
> >
> > +void __init free_early_init_fdt_scan_reserved_mem(void)
> > +{
> > +	unsigned long start, end, size;
> > +	if (!initial_boot_params)
> > +		return;
> > +
> > +	size = fdt_totalsize(initial_boot_params);
> > +	memblock_free(__pa(initial_boot_params), size);
> > +	start = round_down((unsigned long)initial_boot_params, PAGE_SIZE);
> > +	end = round_up((unsigned long)initial_boot_params + size, PAGE_SIZE);
> > +	free_reserved_area((void *)start, (void *)end, 0, "fdt");
> > +	initial_boot_params = 0;
> > +}
> > +
> >  /**
> >   * of_scan_flat_dt - scan flattened tree blob and call callback on each.
> >   * @it: callback function
> > diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h index
> > 0ff360d..21d51ce 100644
> > --- a/include/linux/of_fdt.h
> > +++ b/include/linux/of_fdt.h
> > @@ -62,6 +62,7 @@ extern int early_init_dt_scan_chosen(unsigned long
> > node, const char *uname,  extern int early_init_dt_scan_memory(unsigned
> long node, const char *uname,
> >  				     int depth, void *data);
> >  extern void early_init_fdt_scan_reserved_mem(void);
> > +extern void free_early_init_fdt_scan_reserved_mem(void);
> >  extern void early_init_dt_add_memory_arch(u64 base, u64 size);
> > extern int early_init_dt_reserve_memory_arch(phys_addr_t base,
> phys_addr_t size,
> >  					     bool no_map);
> > @@ -89,6 +90,7 @@ extern u64 fdt_translate_address(const void *blob,
> > int node_offset);  extern void of_fdt_limit_memory(int limit);  #else
> > /* CONFIG_OF_FLATTREE */  static inline void
> > early_init_fdt_scan_reserved_mem(void) {}
> > +static inline void free_early_init_fdt_scan_reserved_mem(void) {}
> >  static inline const char *of_flat_dt_get_machine_name(void) { return
> > NULL; }  static inline void unflatten_device_tree(void) {}  static
> > inline void unflatten_and_copy_device_tree(void) {}
> > --
> > 2.1.0
> > --
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