Setting up U-Boot: Difference between revisions

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with xt-gdb and run U-Boot. Then we are going to download a another copy of this identical program with '''tftp'''. The version we
with xt-gdb and run U-Boot. Then we are going to download a another copy of this identical program with '''tftp'''. The version we
are going to download is just the ELF file with the headers and debug information removed. It's just the actual bits that get
are going to download is just the ELF file with the headers and debug information removed. It's just the actual bits that get
loaded into memory. For the new V3 MMU this will typically be loaded into 0x20,000 and for the older V2 MMU this is in the  
loaded into memory. For the new V3 MMU the default '''loadaddr''' is typically 0x20,0000 and for the older V2 MMU this is in the  
Linux mapping equivalent, 0xD0200,000. The default location can be change by setting the U-Boot 'loadaddr' environment variable.
Linux mapping equivalent, 0xD0200,0000. The default location can be change by setting the U-Boot 'loadaddr' environment variable
or by changing the variable '''CONFIG_SYS_LOAD_ADDR''' in the boards U-Boot config file.


Once the virgin copy of the U-Boot program has been loaded into memory, the Flash memory is un-protected and errasd, then the  
Once the virgin copy of the U-Boot program has been loaded into memory, the Flash memory is un-protected and errasd, then the  

Revision as of 04:09, 11 September 2010

LX60 and LX200 U-Boot Installation

(News: The New DC233, with the V3 MMU, is now working. Work is in progress with the Linux 2.6.29-smp kernel to boot from this new U-Boot.

Summary:

U-Boot is a very popular boot loader; especially within the Embedded Linux community. The U-Boot loader runs on the FPGA boards which are equipped with a dip switch, number 8, which can select where the memory location for the reset vector (0XFE00,0000) comes from. With switch number 8 off the board will map the memory at the reset vector to a small block of SRAM located in the I/O block with the UART and Ethernet buffer memory. When switch number 8 is on the Avnet boards map the beginning of the Flash Memory at 0XF800,000 to the reset vector at 0xFE00,000.

What we are going to do here is build a version of U-Boot for your Avnet board and Variant, install that ELF file into memory with xt-gdb and run U-Boot. Then we are going to download a another copy of this identical program with tftp. The version we are going to download is just the ELF file with the headers and debug information removed. It's just the actual bits that get loaded into memory. For the new V3 MMU the default loadaddr is typically 0x20,0000 and for the older V2 MMU this is in the Linux mapping equivalent, 0xD0200,0000. The default location can be change by setting the U-Boot 'loadaddr' environment variable or by changing the variable CONFIG_SYS_LOAD_ADDR in the boards U-Boot config file.

Once the virgin copy of the U-Boot program has been loaded into memory, the Flash memory is un-protected and errasd, then the memory with the U-Boot program in it is copied to the flash memory and protected. Next you will set dip switch 8 on, recycle power on the board, and U-Boot will be accessible via the serial UART at 38400 baud. U-Boot works without any MMU mapping, and should be fine on configurations without an MMU. Only an ethernet and serial interface are required.


A local port to the Xtensa architecture is now available at linux-xtensa.org. See U-Boot Sources (GIT Summary). Or, to access this tree using git directly, use something like:

  $ git clone git://git.linux-xtensa.org/git/u-boot/u-boot-xtensa.git u-boot
  $ cd u-boot

(Note: This path is subject to change.)


The U-Boot git repository has a branch with a HiFi 2 snapshot made for the LX200 SMP HiFi 2 Development Board. With this branch you can simply check out the snapshot_2+SMP branch which includes the binaries which are discussed below:

  $ git clone git://git.linux-xtensa.org/git/u-boot/u-boot-xtensa.git u-boot
  $ cd u-boot
  $ git branch --track snapshot_2+SMP origin/snapshot_2+SMP
  $ git checkout snapshot_2+SMP
  $ ls -l u-boot u-boot.bin tools/mkimage 
    -rwxr-xr-x 1 piet tensilica  45016 2009-12-07 19:40 tools/mkimage           [This is a small program you need to put in your search path to build kernel U-Boot images]
    -rwxr-xr-x 1 piet tensilica 635339 2009-12-07 19:40 u-boot                  [Started with xt-gdb to bring up the 1st instance of a HiFi 2 U-Boot]
    -rwxr-xr-x 1 piet tensilica 144944 2009-12-07 19:40 u-boot.bin              [Loaded by the 1st instance of U-Boot, it's a HiFi2 version of u-boot that will be put in flash]
  $

Unless you are using a U-Boot snapshot you need to build U-Boot for which you must have built the Buildroot toolchain for XTensa core. Set your PATH to point to the toolchain built using buildroot. For example:

  $ export PATH="<workdir>/buildroot/build_xtensa_<cname>/staging_dir/usr/bin:$PATH"
where <cname> is the name of the Xtensa core variant you wish to build for (e.g., dc232b dc233c).

To build U-Boot, use the cloned git tree pulled above, you should be at the top level of the tree in the u-boot directory , then configure it for your board and Xtensa core variant as follows:

make distclean
make <cname>_<board>_config

'dc232b'dc This should only take a few seconds. For example, to build U-boot for the 'xtav60' board and the older 'dc232b' core with the V2 MMU type:

  $ cd u-boot
  $ make dc232b_xtav60_config                                  [NOTE: You can skip this step with the the HiFi-2 snapshot_2+SMP branch; binaries are pre-built]

or for the new 'dc233c' core with the new V3 MMU type:

  $ make dc233c_xtav60_config                                  [NOTE: You can skip this step with the the HiFi-2 snapshot_2+SMP branch; binaries are pre-built]

or for a 'xtav200' board type with the new 'dc233c' core type:

  $ make dc233c_xtav200_config                                 [NOTE: You can skip this step with the the HiFi-2 snapshot_2+SMP branch; binaries are pre-built]   

or for the snapshot_2+SMP branch you can also build U-Boot for the HiFi 2 core:

  $ make test_mmuhifi_c3_xtav200_config                              [NOTE: You can skip this step with the the HiFi-2 snapshot_2+SMP branch; binaries are pre-built]


Only boards and core variants currently supported in the tree can be built out of the box. Headers for supported cores can be found in the tree under include/asm-xtensa/variant-<cname>. The core specific headers are described in the doc/README.xtensa file. To support a new core, these headers must be copied from the overlay in the same way as for the linux kernel.

After the configuration step, to actually build U-Boot, simply:

  $ make all                                                   [NOTE: You can skip this step with the the HiFi-2 snapshot_2+SMP branch; binaries are pre-built]

This will take a quite a few minutes.

Next, start xt-gdb and load u-boot from the top of the git repository:

  $ xt-gdb -n                                                  [NOTE: Even with the HiFi 2 snapshot_2+SMP branch you still may have to put U-Boot on the board]            
  (xt-gdb) file u-boot
  (xt-gdb) target remote localhost:20000 0
  (xt-gdb) reset
  (xt-gdb) load
  (xt-gdb) break panic
  (xt-gdb) continue

Hopefully U-Boot will start, and display on the LCD in the case of a LX60.

 U-Boot 50.00 Mhz

Often you will be starting with the boards flash in an unknown state and it's best to unprotect and erase the entire flash. Just type protect off all followed by erase all:

   U-Boot> protect off all
   Un-Protect Flash Bank # 1
   ................................................................................................................................... done
   U-Boot>  erase all
   Erase Flash Bank # 1 
   ..........................................................................................................
   Flash erase timeout at address f8d40000 da0
   Flash erase error at address f8d40000
   ........................ done
   U-Boot> 

The timeout and error messages are likley just warning messages and you board has been errased. You can see that with the flash info command flinfo. Below is an example with a LX200 board, which has a much larger flash than the smaller LX60:

  U-Boot> flinfo
   Bank # 1: CFI conformant FLASH (16 x 16)  Size: 16 MB in 131 Sectors
     Intel Extended command set, Manufacturer ID: 0x89, Device ID: 0x18
     Erase timeout: 4096 ms, write timeout: 1 ms
     Buffer write timeout: 2 ms, buffer size: 64 bytes
     Sector Start Addresses:
     F8000000 E      F8020000 E      F8040000 E      F8060000 E      F8080000 E
     F80A0000 E      F80C0000 E      F80E0000 E      F8100000 E      F8120000 E
     F8140000 E      F8160000 E      F8180000 E      F81A0000 E      F81C0000 E
     F81E0000 E      F8200000 E      F8220000 E      F8240000 E      F8260000 E
     F8280000 E      F82A0000 E      F82C0000 E      F82E0000 E      F8300000 E
     F8320000 E      F8340000 E      F8360000 E      F8380000 E      F83A0000 E
     F83C0000 E      F83E0000 E      F8400000 E      F8420000 E      F8440000 E
     F8460000 E      F8480000 E      F84A0000 E      F84C0000 E      F84E0000 E
     F8500000 E      F8520000 E      F8540000 E      F8560000 E      F8580000 E
     F85A0000 E      F85C0000 E      F85E0000 E      F8600000 E      F8620000 E
     F8640000 E      F8660000 E      F8680000 E      F86A0000 E      F86C0000 E
     F86E0000 E      F8700000 E      F8720000 E      F8740000 E      F8760000 E
     F8780000 E      F87A0000 E      F87C0000 E      F87E0000 E      F8800000 E
     F8820000 E      F8840000 E      F8860000 E      F8880000 E      F88A0000 E
     F88C0000 E      F88E0000 E      F8900000 E      F8920000 E      F8940000 E
     F8960000 E      F8980000 E      F89A0000 E      F89C0000 E      F89E0000 E
     F8A00000 E      F8A20000 E      F8A40000 E      F8A60000 E      F8A80000 E
     F8AA0000 E      F8AC0000 E      F8AE0000 E      F8B00000 E      F8B20000 E
     F8B40000 E      F8B60000 E      F8B80000 E      F8BA0000 E      F8BC0000 E
     F8BE0000 E      F8C00000 E      F8C20000 E      F8C40000 E      F8C60000 E
     F8C80000 E      F8CA0000 E      F8CC0000 E      F8CE0000 E      F8D00000 E
     F8D20000 E      F8D40000 E      F8D60000 E      F8D80000 E      F8DA0000 E
     F8DC0000 E      F8DE0000 E      F8E00000 E      F8E20000 E      F8E40000 E
     F8E60000 E      F8E80000 E      F8EA0000 E      F8EC0000 E      F8EE0000 E
     F8F00000 E      F8F20000 E      F8F40000 E      F8F60000 E      F8F80000 E
     F8FA0000 E      F8FC0000 E      F8FE0000 E      F8FE8000 E      F8FF0000 E
     F8FF8000 E
   U-Boot>

Now set your preliminary U-Boot environment variables to point to your TFTP server so we can download yet another copy of U-Boot. At Tensilica we use a machine in the RTOS group called rtos-lab2. Folks using the SMP HiFi 2 Development Board likely have set up their workstation with a TFTP server.

   U-Boot> setenv serverip 192.168.11.78           rtos-lab2

or

   U-Boot> setenv serverip 192.168.11.55           pdelaney_fc9
   U-Boot> setenv ipaddr 192.168.11.95            I/P address of RTOS5, Piet's LX60; MAC: 00:05:C2:13:6f:0a
   U-Boot> setenv bootfile u-boot.bin
   U-Boot> saveenv
   Saving Environment to Flash...
   .... done
   Un-Protected 4 sectors
   Erasing Flash...
   .... done
   Erased 4 sectors
   Writing to Flash... done
   .... done
   Protected 4 sectors
   U-Boot>


Next, download u-boot.bin from the tftp server using the info we just entered into U-Boot's enviroment variables. Here for example is the case for a LX60 running the HiFi-2 Bitstream with the older V2 MMU. Note that it starts up in the D-gazillion (0XD0000000) region:

   U-Boot> tftpboot
   TFTP from server 192.168.11.78; our IP address is 192.168.11.95
   Filename 'u-boot.bin'.
   Load address: 0xd2000000
   Loading: T ########
   done
   Bytes transferred = 107592 (1a448 hex)

For the V3 MMU U-Boot is loaded from host pdelaney_fc9 into memory with virtual == physical. Here is a DC233L, with V3 MMU, example:

   U-Boot> tftpboot
   Using open_ethernet device
   TFTP from server 192.168.11.55; our IP address is 192.168.11.95
   Filename 'u-boot.bin'.
   Load address: 0x2000000
   Loading: T ########
   done
   Bytes transferred = 109964 (1ad8c hex)
   U-Boot>

Now things get a bit tricky here for the LX60. The FLASG has Two sizes of Flash Sectors. The first 8 sectors are small 0x2000 (8KB) and apparently intended for parameters. The rest of the 4MB flash is composed of larger 0x10000 (64KB) sectors. Our code doesn't differentiate between the sectors and the LX60 hardware is going to map 0XF800,0000 to 0XFE00,0000 so this makes us use of all 8 of the 8KB sectors and the 1st 64KB sector at F8010000. So we are going to flash up to F801FFFF below.


On a LX200 we have much more space and can easily fit a version of U-boot that has been compiled without optimization, make debugging much easier. So in this case the image is a bit larger, but relatively similar to the LX60 (2 sectors):

   U-Boot> tftpboot
   Using open_ethernet device
   TFTP from server 192.168.11.78; our IP address is 192.168.11.95
   Filename 'u-boot.bin'.
   Load address: 0xd2000000
   Loading: ###############
   done
   Bytes transferred = 205852 (3241c hex)
   U-Boot>


Note that for both the LX200 and the LX60 that the image size, (3241c hex) in this case, is a bit less than 0x40000 or 10 sectors, so turn off protection on the 1st 11 sectors and erase the current contents.

For the LX60 you do this:

 U-Boot> protect off F8000000 F801FFFF
 ... done
 Un-Protected 2 sectors
 U-Boot> erase F8000000 F801FFFF
       erase F8000000 F801FFFF
       ... done

For the LX200 the starting address (F8000000) is the same as with the LX60 but the last addesss (F803FFFF) is 'twice' as high:

 U-Boot> protect off F8000000 F803FFFF
 ... done
 Un-Protected 2 sectors
 U-Boot> erase F8000000 F803FFFF
 Erased 2 sectors
 U-Boot> 


Now copy the the image of u-boot.bin in memory to the flash. For the XL60 with the OLD V2 MMU you copy 0x20000 bytes from 0xd2000000 to 0XF8000000:

 U-Boot> cp.b d2000000 F8000000 20000
 Copy to Flash... done


For the LX60 with the NEW V3 MMU you copy 0x24000 bytes from 0x2000000 to F8000000:

 U-Boot> cp.b 2000000 F8000000 20000
 Copy to Flash... done

For the LX200 you copy 0x40000 bytes from 0xd2000000 to 0XF8000000...0XF803FFFF:

 U-Boot> cp.b d2000000 F8000000 40000
 Copy to Flash... done

Finally we protect these sectors so that U-Boot isn't easily erased by accident. Below is what it looks like on a LX60 with the New V3 MMU with a subsequent display of the flash info:

   U-Boot> cp.b 2000000 F8000000 2000
   Copy to Flash... done
   U-Boot> flinfo

   Bank # 1: CFI conformant FLASH (16 x 16)  Size: 4 MB in 71 Sectors
     AMD Standard command set, Manufacturer ID: 0x20, Device ID: 0x2257
     Erase timeout: 8192 ms, write timeout: 1 ms

     Sector Start Addresses:
     F8000000        F8002000        F8004000        F8006000        F8008000
     F800A000        F800C000        F800E000        F8010000        F8020000 E
     F8030000 E      F8040000 E      F8050000 E      F8060000 E      F8070000 E
     F8080000 E      F8090000 E      F80A0000 E      F80B0000 E      F80C0000 E
     F80D0000 E      F80E0000 E      F80F0000 E      F8100000 E      F8110000 E
     F8120000 E      F8130000 E      F8140000 E      F8150000 E      F8160000 E
     F8170000 E      F8180000 E      F8190000 E      F81A0000 E      F81B0000 E
     F81C0000 E      F81D0000 E      F81E0000 E      F81F0000 E      F8200000 E
     F8210000 E      F8220000 E      F8230000 E      F8240000 E      F8250000 E
     F8260000 E      F8270000 E      F8280000 E      F8290000 E      F82A0000 E
     F82B0000 E      F82C0000 E      F82D0000 E      F82E0000 E      F82F0000 E
     F8300000 E      F8310000 E      F8320000 E      F8330000 E      F8340000 E
     F8350000 E      F8360000 E      F8370000 E      F8380000 E      F8390000 E
     F83A0000 E      F83B0000 E      F83C0000 E      F83D0000 E      F83E0000
     F83F0000   RO
   U-Boot> protect on F8000000 F802FFFF
   .......... done
   Protected 10 sectors
   U-Boot>
   
   U-Boot> flinfo

   Bank # 1: CFI conformant FLASH (16 x 16)  Size: 4 MB in 71 Sectors
     AMD Standard command set, Manufacturer ID: 0x20, Device ID: 0x2257
     Erase timeout: 8192 ms, write timeout: 1 ms

     Sector Start Addresses:
     F8000000   RO   F8002000   RO   F8004000   RO   F8006000   RO   F8008000   RO
     F800A000   RO   F800C000   RO   F800E000   RO   F8010000   RO   F8020000 E
     F8030000 E      F8040000 E      F8050000 E      F8060000 E      F8070000 E
     F8080000 E      F8090000 E      F80A0000 E      F80B0000 E      F80C0000 E
     F80D0000 E      F80E0000 E      F80F0000 E      F8100000 E      F8110000 E
     F8120000 E      F8130000 E      F8140000 E      F8150000 E      F8160000 E
     F8170000 E      F8180000 E      F8190000 E      F81A0000 E      F81B0000 E
     F81C0000 E      F81D0000 E      F81E0000 E      F81F0000 E      F8200000 E
     F8210000 E      F8220000 E      F8230000 E      F8240000 E      F8250000 E
     F8260000 E      F8270000 E      F8280000 E      F8290000 E      F82A0000 E
     F82B0000 E      F82C0000 E      F82D0000 E      F82E0000 E      F82F0000 E
     F8300000 E      F8310000 E      F8320000 E      F8330000 E      F8340000 E
     F8350000 E      F8360000 E      F8370000 E      F8380000 E      F8390000 E
     F83A0000 E      F83B0000 E      F83C0000 E      F83D0000 E      F83E0000  
     F83F0000   RO
   U-Boot>


Below is what it looks like on a LX200 with the V2 MMU with a subsequent display of the flash info. Notice that the Flash Sectors are 10X as large on the LX200:

  U-Boot> protect on F8000000 F802FFFF
   .. done
   Protected 2 sectors
   U-Boot> flinfo
   Bank # 1: CFI conformant FLASH (16 x 16)  Size: 16 MB in 131 Sectors
     Intel Extended command set, Manufacturer ID: 0x89, Device ID: 0x18
     Erase timeout: 4096 ms, write timeout: 1 ms
     Buffer write timeout: 2 ms, buffer size: 64 bytes
     Sector Start Addresses:
     F8000000   RO   F8020000   RO   F8040000 E      F8060000 E      F8080000 E
     F80A0000 E      F80C0000 E      F80E0000 E      F8100000 E      F8120000 E
     F8140000 E      F8160000 E      F8180000 E      F81A0000 E      F81C0000 E
     F81E0000 E      F8200000 E      F8220000 E      F8240000 E      F8260000 E
     F8280000 E      F82A0000 E      F82C0000 E      F82E0000 E      F8300000 E
     F8320000 E      F8340000 E      F8360000 E      F8380000 E      F83A0000 E
     F83C0000 E      F83E0000 E      F8400000 E      F8420000 E      F8440000 E
     F8460000 E      F8480000 E      F84A0000 E      F84C0000 E      F84E0000 E
     F8500000 E      F8520000 E      F8540000 E      F8560000 E      F8580000 E
     F85A0000 E      F85C0000 E      F85E0000 E      F8600000 E      F8620000 E
     F8640000 E      F8660000 E      F8680000 E      F86A0000 E      F86C0000 E
     F86E0000 E      F8700000 E      F8720000 E      F8740000 E      F8760000 E
     F8780000 E      F87A0000 E      F87C0000 E      F87E0000 E      F8800000 E
     F8820000 E      F8840000 E      F8860000 E      F8880000 E      F88A0000 E
     F88C0000 E      F88E0000 E      F8900000 E      F8920000 E      F8940000 E
     F8960000 E      F8980000 E      F89A0000 E      F89C0000 E      F89E0000 E
     F8A00000 E      F8A20000 E      F8A40000 E      F8A60000 E      F8A80000 E
     F8AA0000 E      F8AC0000 E      F8AE0000 E      F8B00000 E      F8B20000 E
     F8B40000 E      F8B60000 E      F8B80000 E      F8BA0000 E      F8BC0000 E
     F8BE0000 E      F8C00000 E      F8C20000 E      F8C40000 E      F8C60000 E
     F8C80000 E      F8CA0000 E      F8CC0000 E      F8CE0000 E      F8D00000 E
     F8D20000 E      F8D40000 E      F8D60000 E      F8D80000 E      F8DA0000 E
     F8DC0000 E      F8DE0000 E      F8E00000 E      F8E20000 E      F8E40000 E
     F8E60000 E      F8E80000 E      F8EA0000 E      F8EC0000 E      F8EE0000 E
     F8F00000 E      F8F20000 E      F8F40000 E      F8F60000 E      F8F80000 E
     F8FA0000 E      F8FC0000 E      F8FE0000   RO   F8FE8000   RO   F8FF0000   RO
     F8FF8000   RO
   U-Boot>

Note that the U-Boot saveenv command Erased and protected the last four sectors of this LX200.

On both the LX60 and the LX200 now move DIP switch 8 to the ON position, power cycle the board. On the LX60 you should see U-boot in the LCD display.

The LX60 with the new V3 MMU the serial console should print something like the following:

  U-Boot 2009.08-dirty (Sep 10 2010 - 18:23:26)

   CPU:    Xtensa dc233c at 50.00 MHz
   Board:  XT-AV60: Avnet board + Xilinx LX60 FPGA + Tensilica bitstream
   SysRAM: 64 MB
   Flash:  4 MB
   In:    serial
   Out:   serial
   Err:   serial
   MAC:    00:50:C2:13:6f:0a
   IP:     192.168.11.95
   open_ethernet
   U-Boot>     


On the LX200, shown below with the old V2 MMU, you should see something like the following. In this case we also show the flash info command, flinfo, being invoked just after booting U-Boot:

  CPU:    Xtensa test_mmuhifi_c3 at 41.6777 MHz
   Board:  XT-AV200: Avnet board + Xilinx LX200 FPGA + Tensilica bitstream
   SysRAM: 96 MB
   Flash: 16 MB
   In:    serial
   Out:   serial
   Err:   serial
   MAC:
   IP:     192.168.11.95
   U-Boot>
   U-Boot> flinfo
   Bank # 1: CFI conformant FLASH (16 x 16)  Size: 16 MB in 131 Sectors
     Intel Extended command set, Manufacturer ID: 0x89, Device ID: 0x18
     Erase timeout: 4096 ms, write timeout: 1 ms
     Buffer write timeout: 2 ms, buffer size: 64 bytes
     Sector Start Addresses:
     F8000000   RO   F8020000   RO   F8040000 E RO   F8060000 E RO   F8080000 E RO
     F80A0000 E RO   F80C0000 E RO   F80E0000 E RO   F8100000 E RO   F8120000 E RO
     F8140000 E RO   F8160000 E RO   F8180000 E RO   F81A0000 E RO   F81C0000 E RO
     F81E0000 E RO   F8200000 E RO   F8220000 E RO   F8240000 E RO   F8260000 E RO
     F8280000 E RO   F82A0000 E RO   F82C0000 E RO   F82E0000 E RO   F8300000 E RO
     F8320000 E RO   F8340000 E RO   F8360000 E RO   F8380000 E RO   F83A0000 E RO
     F83C0000 E RO   F83E0000 E RO   F8400000 E RO   F8420000 E RO   F8440000 E RO
     F8460000 E RO   F8480000 E RO   F84A0000 E RO   F84C0000 E RO   F84E0000 E RO
     F8500000 E RO   F8520000 E RO   F8540000 E RO   F8560000 E RO   F8580000 E RO
     F85A0000 E RO   F85C0000 E RO   F85E0000 E RO   F8600000 E RO   F8620000 E RO
     F8640000 E RO   F8660000 E RO   F8680000 E RO   F86A0000 E RO   F86C0000 E RO
     F86E0000 E RO   F8700000 E RO   F8720000 E RO   F8740000 E RO   F8760000 E RO
     F8780000 E RO   F87A0000 E RO   F87C0000 E RO   F87E0000 E RO   F8800000 E RO
     F8820000 E RO   F8840000 E RO   F8860000 E RO   F8880000 E RO   F88A0000 E RO
     F88C0000 E RO   F88E0000 E RO   F8900000 E RO   F8920000 E RO   F8940000 E RO
     F8960000 E RO   F8980000 E RO   F89A0000 E RO   F89C0000 E RO   F89E0000 E RO
     F8A00000 E RO   F8A20000 E RO   F8A40000 E RO   F8A60000 E RO   F8A80000 E RO
     F8AA0000 E RO   F8AC0000 E RO   F8AE0000 E RO   F8B00000 E RO   F8B20000 E RO
     F8B40000 E RO   F8B60000 E RO   F8B80000 E RO   F8BA0000 E RO   F8BC0000 E RO
     F8BE0000 E RO   F8C00000 E RO   F8C20000 E RO   F8C40000 E RO   F8C60000 E RO
     F8C80000 E RO   F8CA0000 E RO   F8CC0000 E RO   F8CE0000 E RO   F8D00000 E RO
     F8D20000 E RO   F8D40000 E RO   F8D60000 E RO   F8D80000 E RO   F8DA0000 E RO
     F8DC0000 E RO   F8DE0000 E RO   F8E00000 E RO   F8E20000 E RO   F8E40000 E RO
     F8E60000 E RO   F8E80000 E RO   F8EA0000 E RO   F8EC0000 E RO   F8EE0000 E RO
     F8F00000 E RO   F8F20000 E RO   F8F40000 E RO   F8F60000 E RO   F8F80000 E RO
     F8FA0000 E RO   F8FC0000 E RO   F8FE0000   RO   F8FE8000   RO   F8FF0000   RO
     F8FF8000   RO
   U-Boot>


Note that the 1st two sectors with U-Boot saved in them came up as not being erased (E) but that all sectors came up Read Only (RO). Same with the last four sectors that the U-Boot saveenv command Erased. This is likely a bug that we have been investigating and will be discussing with the U-Boot developers sometime in the future prior to pushing our U-boot changes upstream.


Further details on U-Boot in general are in the generic README at the top of the U-Boot tree. Details specific to the Xtensa architecture are in doc/README.xtensa. Details specific to a board are in board[/<family>]/<board>/README (for example board/avnet/xtav60/README).