[U-Boot] [PATCH] fix print_size printing fractional gigabyte numbers on 32-bit platforms

[Scott Wood]

Timur Tabi wrote:
> In print_size(), the math that calculates the fractional remainder of a number
> used the same integer size as a physical address.  However, the "10 *" factor
> of the algorithm means that a large number (e.g. 1.5GB) can overflow the
> integer if we're running on a 32-bit system.  Therefore, we need to
> disassociate this function from the size of a physical address.
> 
> Signed-off-by: Timur Tabi <timur at freescale.com>
> ---
>  include/common.h              |    2 +-
>  lib_generic/display_options.c |    5 ++---
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/include/common.h b/include/common.h
> index a133e34..4e77727 100644
> --- a/include/common.h
> +++ b/include/common.h
> @@ -218,7 +218,7 @@ void	hang		(void) __attribute__ ((noreturn));
>  /* */
>  phys_size_t initdram (int);
>  int	display_options (void);
> -void	print_size (phys_size_t, const char *);
> +void	print_size(unsigned long long, const char *);
>  int	print_buffer (ulong addr, void* data, uint width, uint count, uint linelen);
>  
>  /* common/main.c */
> diff --git a/lib_generic/display_options.c b/lib_generic/display_options.c
> index 2dc2567..cafb603 100644
> --- a/lib_generic/display_options.c
> +++ b/lib_generic/display_options.c
> @@ -43,10 +43,9 @@ int display_options (void)
>   * xxx GB, or xxx.y GB as needed; allow for optional trailing string
>   * (like "\n")
>   */
> -void print_size (phys_size_t size, const char *s)
> +void print_size(unsigned long long size, const char *s)
>  {
> -	ulong m = 0, n;
> -	phys_size_t d = 1 << 30;		/* 1 GB */
> +	unsigned long m = 0, n, d = 1 << 30 /* 1 GB */;
>  	char  c = 'G';

In changing "d" from phys_size_t to unsigned long, I think you're 
introducing overflow in "n * d" (consider 5.5G rather than 1.5G).

Wouldn't a more straightforward fix, that doesn't affect the function 
signature, be to just change "10 *" to "10ULL *"?

-Scott