symbiflow working? which boards do work correcty for Xilinx 7 series?

[cacona666]

Hi there,

Thanks a lot for your work!

I tried to use symbiflow toolchain and I couldn't make it work. I am using current master branch revision for litex-boards and linux-on-litex-vexriscv.

When using --board=arty like this: ./make.py --board=arty --toolchain=symbiflow --build

I end up getting the following error:

symbiflow_synth -t arty -v /home/juan/Development/platforms/riscv/vexriscv/pythondata-cpu-vexriscv-smp/pythondata_cpu_vexriscv_smp/verilog/Ram_1w_1rs_Generic.v /home/juan/Development/platforms/riscv/vexriscv/pythondata-cpu-vexriscv-smp/pythondata_cpu_vexriscv_smp/verilog/VexRiscvLitexSmpCluster_Cc1_Iw32Is4096Iy1_Dw32Ds4096Dy1_ITs4DTs4_Ldw128_Ood.v /home/juan/Development/platforms/riscv/vexriscv/linux-on-litex-vexriscv/build/arty/gateware/arty.v -d artix7 -p xc7a35tcsg324-1 -x arty.xdc > /dev/null
**ERROR: Cell $iopadmap$arty.sdcard_cd of type \IBUF doesn't support the \SLEW attribute**

When using --board=arty_a7 I get a similar one: **ERROR: Cell $iopadmap$arty_a7.sdcard_cd of type \IBUF doesn't support the \SLEW attribute** And when using the nexys4ddr it just tries to use Vivado toolchain:

OSError: Unable to find or source Vivado toolchain, please either:
- Source Vivado's settings manually.
- Or set LITEX_ENV_VIVADO environment variant to Vivado's settings path.
- Or add Vivado toolchain to your $PATH.

Symbiflow Xilinx 7 series examples include a 'Linux LiteX demo' example with "arty_100" target that builds correctly (haven't run them).

Question: Is this a known problem or I am doing something wrong? Question: I plan to use the "nexy4ddr" target. Will it be possible/easy to make it work with current board configuration? Question: Is it ok to use symbiflow or the recommendation is still to use Vivado for Litex?

Thanks!

[mithro]

PTAL - @kgugala

[mithro]

FYI - https://symbiflow-examples.readthedocs.io/en/latest/building-examples.html#linux-litex-demo

[tanakamura]

I got same problem.

It looks some primitives or attributes of primitive are not supported by current symbiflow.

Therefore, it seems that the following units cannot be synthsized currently.

• sdcard
• jtagbone
• xadc,
• icap_bitstream

To use symbiflow, I added some workarounds to remove these units.

diff --git a/make.py b/make.py
index 1d050a7..e5c486b 100755
--- a/make.py
+++ b/make.py
@@ -58,6 +58,10 @@ class AcornCLE215(Board):
 # Arty support -------------------------------------------------------------------------------------

 class Arty(Board):
+    soc_kwargs = {
+        "sys_clk_freq" : int(80e6), # Increase sys_clk_freq to 64MHz (48MHz default).
+    }
+
     spiflash = S25FL128L(Codes.READ_1_1_1)
     def __init__(self):
         from litex_boards.targets import arty
@@ -67,7 +71,7 @@ class Arty(Board):
             "ethernet",
             # Storage
             "spiflash",
-            "sdcard",
+            #"sdcard",
             # GPIOs
             "leds",
             "rgb_led",
@@ -76,10 +80,10 @@ class Arty(Board):
             "spi",
             "i2c",
             # Monitoring
-            "xadc",
+            #"xadc",
             # 7-Series specific
             "mmcm",
-            "icap_bitstream",
+            #"icap_bitstream",
         }, bitstream_ext=".bit")

 class ArtyA7(Arty): pass
@@ -591,6 +595,9 @@ def main():
         if "framebuffer" in board.soc_capabilities:
             soc_kwargs.update(with_video_framebuffer=True)

+        if args.toolchain == "symbiflow":
+            soc_kwargs.update(with_jtagbone=False)
+
         # SoC creation -----------------------------------------------------------------------------
         soc = SoCLinux(board.soc_cls, **soc_kwargs)
         board.platform = soc.platform

(I cannot run bitstream synthesized by symbiflow at 100MHz. This diff reduces sys_clock to 80MHz)

[mithro]

It would be good to log issues with SymbiFlow about which functionality needs to be added to make this work out of box.

[enjoy-digital]

The boards well supported by Symbiflow are probably listed in Symbiflow project. For designs with LiteX, the Digilent Arty is the one tested more regularly and recommended.