Subject: Re: [PATCH: dtc] Improve -S handling

From: David Gibson <[email-masked]>
Date: Wed, 18 Apr 2007 13:05:28 +1000

On Tue, Apr 17, 2007 at 10:05:35PM -0400, Jerry Van Baren wrote:
> If the user requests extra space, pad out the blob (previously the unused
>   data was undefined).
> 
> Signed-off-by: Gerald Van Baren <[email-masked]>
> ---
> 
> Hi Jon, David, Milton,
> 
> This improves the -S option to pad out the blob with zeros when the user
> asks for extra space.

Comment below
> diff --git a/flattree.c b/flattree.c
> index 151d16e..d2ee0dc 100644
> --- a/flattree.c
> +++ b/flattree.c
> @@ -310,6 +310,7 @@ static struct data flatten_reserve_list(struct reserve_info *reservelist,
>  	
>  	return d;
>  }
> +
>  static void make_bph(struct boot_param_header *bph,
>  		     struct version_info *vi,
>  		     int reservesize, int dtsize, int strsize,
> @@ -358,12 +359,15 @@ void dt_to_blob(FILE *f, struct boot_info *bi, int version,
>  {
>  	struct version_info *vi = NULL;
>  	int i;
> +	int size;
>  	struct data dtbuf = empty_data;
>  	struct data strbuf = empty_data;
>  	struct data reservebuf;
>  	struct boot_param_header bph;
>  	struct reserve_entry termre = {.address = 0, .size = 0};
>  
> +	size = 0;
> +
>  	for (i = 0; i < ARRAY_SIZE(version_table); i++) {
>  		if (version_table[i].version == version)
>  			vi = &version_table[i];
> @@ -384,10 +388,13 @@ void dt_to_blob(FILE *f, struct boot_info *bi, int version,
>  		 boot_cpuid_phys);
>  
>  	fwrite(&bph, vi->hdr_size, 1, f);
> +	size += vi->hdr_size;
>  
>  	/* Align the reserve map to an 8 byte boundary */
> -	for (i = vi->hdr_size; i < be32_to_cpu(bph.off_mem_rsvmap); i++)
> +	for (i = vi->hdr_size; i < be32_to_cpu(bph.off_mem_rsvmap); i++) {
>  		fputc(0, f);
> +		size += 1;
> +	}
>  
>  	/*
>  	 * Reserve map entries.
> @@ -396,9 +403,27 @@ void dt_to_blob(FILE *f, struct boot_info *bi, int version,
>  	 */
>  	fwrite(reservebuf.val, reservebuf.len, 1, f);
>  	fwrite(&termre, sizeof(termre), 1, f);
> +	size += reservebuf.len + sizeof(termre);
>  
>  	fwrite(dtbuf.val, dtbuf.len, 1, f);
>  	fwrite(strbuf.val, strbuf.len, 1, f);
> +	size += dtbuf.len + strbuf.len;
> +
> +	/*
> +	 * If the user asked for more space than is used, pad it out.
> +	 */
> +	if (minsize > 0) {
> +		int padlen = minsize - size;
> +
> +		if (padlen > 0) {
> +			char *zeroes = calloc(padlen, 1);
> +
> +			if (zeroes != NULL) {
> +				fwrite(zeroes, padlen, 1, f);
> +				free(zeroes);
> +			}
> +		}
> +	}

Hrm, rather than all this explicit calloc() mangling, I'd prefer we
use our existing struct data stuff.  Use data_append_zeroes() on
empty_data to generate your buffer of padding.

>  	if (ferror(f))
>  		die("Error writing device tree blob: %s\n", strerror(errno));
> @@ -504,6 +529,14 @@ void dt_to_asm(FILE *f, struct boot_info *bi, int version, int boot_cpuid_phys)
>  
>  	emit_label(f, symprefix, "blob_end");
>  
> +	/*
> +	 * If the user asked for more space than is used, pad it out.
> +	 */
> +	if (minsize > 0) {
> +		fprintf(f, "\t.space\t%d - (%s_blob_end - %s_blob_start), 0\n", 
> +			minsize, symprefix, symprefix);
> +	}
> +
>  	data_free(strbuf);
>  }
>  

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson