# Pynq SD card boot error (prebuilt\_image using BSP)

**URL:** <https://discuss.pynq.io/t/pynq-sd-card-boot-error-prebuilt-image-using-bsp/3246>\
**Category:** Support\
**Created:** [November 3, 2021, 2:35pm UTC](https://discuss.pynq.io/t/pynq-sd-card-boot-error-prebuilt-image-using-bsp/3246 "2021-11-03T14:35:25Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![vijaykumarvg1](https://avatars.discourse-cdn.com/v4/letter/v/b38774/32.png) [@vijaykumarvg1](https://discuss.pynq.io/u/vijaykumarvg1)\
**Post date:** [November 3, 2021, 2:35pm UTC](https://discuss.pynq.io/t/pynq-sd-card-boot-error-prebuilt-image-using-bsp/3246/1 "2021-11-03T14:35:25Z")

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Hi,

Pynq git version: master  
Ubuntu version: 18.04.6 LTS  
Vivado version: 2020.1  
Petalinux version: 2020.1

I am using the above-mentioned versions to build Pynq overlay using the prebuilt image command. Using BSP file, which is built using petalinux 2020.1

Using coustom Ultrscale+ board (part xczu4ev-sfvc784-1-i )

Command to build Pynq Image: **bash scriptpts/image\_from\_prebuilt.sh Boardname Boards.bsp aarch64 bionic.aarch64.2.6.0\_2020\_10\_19.img**

I successfully generated the image file, when I write this image file to sd-card using windisk manager boot it in custom FPGA board I get the following error:

–end kernel panic -not syncing : VFS: unable to mount root f-

Tried different ways mentioned to write image file but no luck, I tried just with BSP petalinux bootable file writing to SD card works fine.

Here attaching complete log [log.txt](https://discuss.pynq.io/uploads/short-url/aiQALtiKhSerV81Pjm7Iuid8r6t.txt) (35.6 KB)

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<div class="post-metadata">

**Author:** ![vijaykumarvg1](https://avatars.discourse-cdn.com/v4/letter/v/b38774/32.png) [@vijaykumarvg1](https://discuss.pynq.io/u/vijaykumarvg1)\
**Post date:** [November 4, 2021, 8:44am UTC](https://discuss.pynq.io/t/pynq-sd-card-boot-error-prebuilt-image-using-bsp/3246/2 "2021-11-04T08:44:04Z")

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I am thinking if there are any options I need to choose while generating the BSP file for PYNQ. I did keep everything default and built the project.

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**Author:** ![skalade](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.pynq.io/skalade/32/686_2.png) [@skalade](https://discuss.pynq.io/u/skalade)\
**Post date:** [November 5, 2021, 12:43am UTC](https://discuss.pynq.io/t/pynq-sd-card-boot-error-prebuilt-image-using-bsp/3246/3 "2021-11-05T00:43:45Z")

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Hi,

How big is your SD card and is it the only SD card you’ve tried? I also wonder if you could mount the root partition on your host machine as a sanity check just to see if you can actually access files there.

If it’s a write protection issue, a solution to a similar problem has been shown in [this forum post](https://support.xilinx.com/s/question/0D52E00006mfjcg/vfs-cannot-open-root-device-mmcblk0p2-or-unknownblock1792-error-30-kria-kv260?language=en_US), you might be able to make this addition to your system-user.dtsi in your petalinux project.

Shawn

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**Author:** ![vijaykumarvg1](https://avatars.discourse-cdn.com/v4/letter/v/b38774/32.png) [@vijaykumarvg1](https://discuss.pynq.io/u/vijaykumarvg1)\
**Post date:** [November 8, 2021, 10:01am UTC](https://discuss.pynq.io/t/pynq-sd-card-boot-error-prebuilt-image-using-bsp/3246/4 "2021-11-08T10:01:09Z")

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Yes thank you, you guessed it right it was a problem with the write protection issue. Where as this issue encounters while building for a custom board. The forum post was helpful. Along with that, I made a few other changes that worked fine in the end.