On Mon, Jan 13, 2020 at 7:55 PM Heinrich Schuchardt <xypron.g...@gmx.de> wrote: > On 1/13/20 5:34 PM, Tom Rini wrote: > > On Mon, Jan 13, 2020 at 12:52:48PM +0200, Andy Shevchenko wrote: > >> Hi! > >> > >> I recently stumble over FAT partitioning issue. I have a device with > >> MMC, one partition of which has been exported as disk via USB Mass > >> Storage to the host. When Windows 10 sees that disk it can't handle it > >> till I format it there. > > This I could reproduce. > > So far so good. However, the same partition > >> can't be used under U-Boot due to Windows flow, i.e. it makes a > >> partitioning on top of the actual partition while U-Boot expects that > >> we only have one MBR (or partitioning) on the dist. So, the commands > >> such fatls, fatload do not recognise any file there. > > But for me the U-Boot's load command loaded a file created on Windows > without problems. The size of my FAT partition was 50 MiB. > > Please, provide a more detailed instruction how to create an image that > is recognized by Windows but not by U-Boot.
Windows GUI (Disk manager by clicking right button on the Windows icon on the bar) provides this. https://www.windowscentral.com/how-format-usb-flash-drive-windows-10 Basically I followed above (Quick or not format makes no difference -- it has the "new simple volume" available only which creates, as mentioned, volume with all structures). > Please, provide a gzipped test image for download. What image? Disk one? Let me prepare it later when I come home. > > Best regards > > Heinrich > > >> > >> In Linux it's easy to use: mount -o loop,offset=65536 /dev/mmcblk0p9 /mnt > >> (offset can be different) > >> > >> But I would like to use it in U-Boot. > >> > >> Any thoughts on this? > > > > I'm not sure. If you didn't have to use offset+loop to re-expose things > > as a new disk and show the partition I'd say we need to support that > > case. But here, hmmm. We don't have "loopback". So, I'm not sure. > > Can't you just tell Windows to use the whole device as FAT and so > > mmcblk0p9 would directly be FAT and work as expected in both Linux and > > U-Boot? > > -- With Best Regards, Andy Shevchenko