Re: [PATCH] of/fdt: add kernel command line option for dtb_compatstring

[Dirk Brandewie]

On 12/06/2010 10:37 AM, Stephen Neuendorffer wrote:
> > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> > index c1360e0..ca1318c 100644
> > --- a/drivers/of/fdt.c
> > +++ b/drivers/of/fdt.c
> > @@ -15,6 +15,8 @@
> >   #include<linux/of_fdt.h>
> >   #include<linux/string.h>
> >   #include<linux/errno.h>
> > +#include<asm-generic/vmlinux.lds.h>
> > +
> >
> >   #ifdef CONFIG_PPC
> >   #include<asm/machdep.h>
> > @@ -604,3 +606,49 @@ void __init unflatten_device_tree(void)
> >
> >   	pr_debug("<- unflatten_device_tree()\n");
> >   }
> > +
> > +extern uint8_t __dtb_start[];
> > +extern uint8_t __dtb_end[];
> > +static void __init *of_flat_dt_find_compatible_dtb(char *name)
> > +{
> > +	void *rc = NULL;
> > +	unsigned long root, size;
> > +	struct boot_param_header  *orig_initial_boot_params;
> > +	uint8_t *blob;
> > +
> > +	orig_initial_boot_params = initial_boot_params;
> > +	blob = __dtb_start;
> > +	initial_boot_params = (struct boot_param_header *)blob;
>
> Oy... can you avoid the pointer dance by using of_fdt_is_compatible()
> from my recent set of patches?

I would like to get rid of the pointer dance. Is your patch set going to make it 
into .37?  I didn't see any acks.

> It takes a blob argument.  Then the loop below goes away.

The loop will still be needed since multiple DTBs may be linked into the image. 
using your  of_fdt_is_compatible() will make the loop a lot more readable though.

--Dirk

> Steve
>
> > +
> > +
> > +	while (blob<  __dtb_end) {
> > +		if (be32_to_cpu(initial_boot_params->magic) !=
> OF_DT_HEADER) {
> > +			WARN(1, "Invalid device tree blob in
> vmlinux\n");
> > +			break;
> > +		}
> > +
> > +		root = of_get_flat_dt_root();
> > +		if (of_flat_dt_is_compatible(root, name)>  0) {
> > +			rc = blob;
> > +			break;
> > +		}
> > +
> > +		size =  be32_to_cpu(initial_boot_params->totalsize);
> > +		blob =  PTR_ALIGN(blob + size, STRUCT_ALIGNMENT);
> > +		initial_boot_params = (struct boot_param_header *)blob;
> > +	}
> > +
> > +	if (rc == NULL)
> > +		initial_boot_params = orig_initial_boot_params;
> > +	return rc;
> > +}
> > +
> > +
> > +static int __init of_flat_dtb_compat_setup(char *line)
> > +{
> > +	if (!initial_boot_params)
> > +		initial_boot_params =
> of_flat_dt_find_compatible_dtb(line);
> > +	return 1;
> > +}
> > +
> > +early_param("dtb_compat", of_flat_dtb_compat_setup);
> > +
> > --
> > 1.7.2.3
> >
> > _______________________________________________
> > devicetree-discuss mailing list
> > devicetree-discuss@xxxxxxxxxxxxxxxx
> > https://lists.ozlabs.org/listinfo/devicetree-discuss
>
>
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