From patchwork Fri Jan 17 10:44:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Shevchenko X-Patchwork-Id: 239717 List-Id: U-Boot discussion From: andriy.shevchenko at linux.intel.com (Andy Shevchenko) Date: Fri, 17 Jan 2020 12:44:51 +0200 Subject: [PATCH v1] doc: README.distro: Special case with Windows formatted disk Message-ID: <20200117104451.62417-1-andriy.shevchenko@linux.intel.com> If someone wants to use shared (by installed OS) eMMC partition to the Windows to boot from, it's not possible due to U-Boot limitations. Describe this case and possible workaround. Signed-off-by: Andy Shevchenko --- doc/README.distro | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/doc/README.distro b/doc/README.distro index ab6e6f4e74..807a82c910 100644 --- a/doc/README.distro +++ b/doc/README.distro @@ -405,3 +405,23 @@ of the boot environment and are not guaranteed to exist or work in the same way in future u-boot versions. In particular the _boot variables (e.g. mmc_boot, usb_boot) are a strictly internal implementation detail and must not be used as a public interface. + +Using a eMMC partition that has been formatted as a disk by Windows 10 +====================================================================== + +Let's assume we have an (embedded) board with U-Boot and Linux OS +installed on eMMC. Linux OS shares one of the eMMC partitions as +a disk via USB Mass Storage protocol. + +It may be useful to utilize that disk to copy bootable files from +Windows machine to the board in case someone doesn't want to erase +stock installation on it. + +Unfortunately, Windows 10 doesn't provide knobs and always formats +that disk as a whole, meaning that it creates a partition table on it +with requested (FAT) partition. As a result U-Boot may not see any +files on it due to nesting partition tables. + +The workaround may be in formatting the partition under Linux OS, +setting up a network connection between Linux OS and Windows 10 and +use it to copy files to the partition.