[U-Boot] [PATCH v3 10/26] fs: fat: support write with non-zero offset

[AKASHI Takahiro]

On Wed, Oct 31, 2018 at 09:54:14PM +0100, Heinrich Schuchardt wrote:
> On 10/31/2018 01:22 PM, Alexander Graf wrote:
> > On 10/31/2018 11:00 AM, Clément Péron wrote:
> >> Hi,
> >>
> >> Trying to rebuild my SoCFPGA Cyclone V board and got this error :
> >>
> >> fs/built-in.o: In function `set_contents':
> >> /home/cperon/u-boot/fs/fat/fat_write.c:831: undefined reference to
> >> `__aeabi_ldivmod'
> >> make: *** [Makefile:1381: u-boot] Error 1
> >>
> >> seems to be introduced with this operation :
> >> assert(!(cur_pos % bytesperclust));
> > 
> > Could we maybe just use a bitmask for bytesperclust?
> > 
> > 
> > Alex
> 
> According to the FAT specification the cluster size is a power of two.
> So we can write

I found:
"Count of bytes per sector. This value may take on
 only the following values: 512, 1024, 2048 or 4096."

> assert(!(cur_pos & (bytesperclust -1)));

It seems reasonably good.

Thanks,
-Takahiro Akashi

> Cf. patch
> https://lists.denx.de/pipermail/u-boot/2018-October/346178.html
> fs: fat: validate sector and cluster size.
> 
> Best regards
> 
> Heinrich