From 9cfc9d20be78142b170624eaa2fac5d72b339e79 Mon Sep 17 00:00:00 2001
From: Michael Huebler <mh@tosl.org>
Date: Sat, 24 Aug 2019 10:30:43 +0000
Subject: [PATCH] Update how-to-build.rst - Note for the case where the file
 size is too big and cannot be flashed (happened on macOS with LC_ALL set to
 UTF8)

---
 Documentation/how-to-build.rst | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/how-to-build.rst b/Documentation/how-to-build.rst
index 14e82431c..0b616ab26 100644
--- a/Documentation/how-to-build.rst
+++ b/Documentation/how-to-build.rst
@@ -143,3 +143,13 @@ In order to do a rebuild you can issue a clean command to ninja via
   $ ninja -C build/ -t clean
 
 Otherwise, rerunning ``./bootstrap.sh`` will also clean the build-directory.
+
+.. note::
+
+   If you try to flash pycardium_epicardium.bin (renamed to card10.bin) 
+   and the bootloader does not finish updating, the file might be too large.
+   ~700kB is the normal size, but problems were reported where the file size 
+   was >1MB. This was caused by the ``tr`` tool in the build process 
+   (it's supposed to create a large file with 0xff in it) - this requires the 
+   LC_ALL environment variable to be not set, or set to "C" 
+   (but not UTF8 or similar).
\ No newline at end of file
-- 
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