Common errors

Note: We will populate this with questions from Piazza when it looks like many people are running into the same issue.

VBoxManage: error: Details: code NS_ERROR_FAILURE…

There was an error while executing `VBoxManage`, a CLI used by Vagrant
for controlling VirtualBox. The command and stderr is shown below.

Command: ["startvm", "...", "--type", "headless"]

Stderr: VBoxManage: error: The virtual machine 'vm-singularity_default_...' has terminated unexpectedly during startup with exit code 1 (0x1)

VBoxManage: error: Details: code NS_ERROR_FAILURE (0x80004005), component MachineWrap, interface IMachine

This is a Vagrant and/or VirtualBox issue, not with Singularity or Chisel. You’ll most likely see this because you ran the following command in the Sylabs Singularity installation guide:

export VM=sylabs/singularity-ubuntu-bionic64 ...

This is the wrong image! To fix this, go back to the folder you created during the tutorial and run vagrant destroy. Then run the following:

cd dinocpu
vagrant up
vagrant ssh

The Vagrantfile in the dinocpu folder is correctly initialized, so doing this should just work.

FATAL: container creation failed: mount error…

If you see the following error, it is likely because you ran out of disk space on the CSIF machine.

FATAL:   container creation failed: mount error: can't mount image /proc/self/fd/8: failed to mount squashfs filesystem: invalid argument

You can find out how much space you’re using with the fquota command as shown below. fquota is a script only on the CSIF machines to help you find the largest directories, so you can clean up your files.

jlp@ad3.ucdavis.edu@pc12:~$ fquota
QUOTA SUMMARY   -- Disk quotas for user jlp@ad3.ucdavis.edu (uid 832205):
Currently using 1717 MB of 2048 MB in your quota.

If you clear your Singularity cache (.singularity/cache/), you can free up some disk space, but the Singularity image will be re-downloaded the next time you run singularity.

[warn] No sbt.version set in project/build.properties…

WARNING: Authentication token file not found : Only pulls of public images will succeed
[warn] No sbt.version set in project/build.properties, base directory: ...
[info] Set current project to ... (in build file: ...)
>

This occurs when you try to run Singularity outside of the dinocpu directory. Run the singularity run command within the dinocpu directory.

Cannot find cpu.registers.regs_5 in symbol table

sbt:dinocpu> testOnly dinocpu.SingleCycleAddTesterLab1
[info] Compiling 1 Scala source to /home/jlp/Code/dinocpu/target/scala-2.12/classes ...
[warn] there were 18 feature warnings; re-run with -feature for details
[warn] one warning found
[info] Done compiling.
[info] [0.001] Elaborating design...
[info] [0.148] Done elaborating.
[info] SingleCycleAddTesterLab1:
[info] Single Cycle CPU
[info] - should run add test add1 *** FAILED ***
[info]   firrtl.passes.CheckInitialization$RefNotInitializedException: @[cpu.scala 22:26] : [module SingleCycleCPU]  Reference registers is not fully initialized.
[info]    : registers.io.wen <= VOID
[info]   at firrtl.passes.CheckInitialization$.$anonfun$run$6(CheckInitialization.scala:79)
[info]   at firrtl.passes.CheckInitialization$.$anonfun$run$6$adapted(CheckInitialization.scala:74)
[info]   at scala.collection.TraversableLike$WithFilter.$anonfun$foreach$1(TraversableLike.scala:789)
[info]   at scala.collection.mutable.HashMap.$anonfun$foreach$1(HashMap.scala:138)
[info]   at scala.collection.mutable.HashTable.foreachEntry(HashTable.scala:236)
[info]   at scala.collection.mutable.HashTable.foreachEntry$(HashTable.scala:229)
[info]   at scala.collection.mutable.HashMap.foreachEntry(HashMap.scala:40)
[info]   at scala.collection.mutable.HashMap.foreach(HashMap.scala:138)
[info]   at scala.collection.TraversableLike$WithFilter.foreach(TraversableLike.scala:788)
[info]   at firrtl.passes.CheckInitialization$.checkInitM$1(CheckInitialization.scala:74)
[info]   ...
[info] ScalaTest
[info] Run completed in 776 milliseconds.
[info] Total number of tests run: 1
[info] Suites: completed 1, aborted 0
[info] Tests: succeeded 0, failed 1, canceled 0, ignored 0, pending 0
[info] *** 1 TEST FAILED ***
[error] Failed: Total 1, Failed 1, Errors 0, Passed 0
[error] Failed tests:
[error]         dinocpu.SingleCycleAddTesterLab1
[error] (test / testOnly) sbt.TestsFailedException: Tests unsuccessful
[error] Total time: 2 s, completed Jan 8, 2019 6:49:17 PM

If you encounter an error saying that the simulator (Treadle) can’t find some register in the symbol table, this is likely because the register file is being optimized away. You will see this error before you add any of your own code. Chisel is an optimizing compiler that checks to see if the hardware will ever be used. If Chisel determines the hardware will never be used, it will remove the hardware.

To fix this error: Make sure that you have connected up the register file correctly. More specifically, check the write enable input to the register file.

possible cause: maybe a semicolon is missing before ‘value is’?

If Chisel complains about a missing semicolon before an is statement it is likely that you have a nested is.

For instance, this is an error you may see.

[error] /home/jlp/dinocpu/src/main/scala/components/alucontrol.scala:40:13: value is is not a member of Unit
[error] possible cause: maybe a semicolon is missing before `value is'?
[error]           } is ("b0100000".U) {

Below is an example incorrect nested is statement.

switch (io.funct3) {
  is ("b000".U) {
    switch (io.funct7) {
      is (xxxxxxx) {
        io.operation := wwwwwwww
      } is (yyyyyyyy) {
        io.operation := zzzzzzzz
      }
    }
  }
  ...

You can fix this by changing the inner switch to a when.

switch (io.funct3) {
  is ("b000".U) {
    when (io.funct7 === xxxxxxx) { io.operation := wwwwwwww }
    otherwise { io.operation := zzzzzzzz }
  }
  ...

java.lang.Exception: Problem with compilation

If you see this error, then your mistake is likely in your Chisel syntax or a type error in Chisel.

For instance, if I try to connect a signed number to an unsigned input I get the following output from Chisel.

class Adder extends Module {
  val io = IO(new Bundle{
    val inputx    = Input(UInt(32.W))
    val inputy    = Input(UInt(32.W))

    val result    = Output(UInt(32.W))
  })

  io.result := io.inputx + io.inputy
}

val pcPlusFour = Module(new Adder())
pcPlusFour.io.inputy := 4.S

The output when I try to run Chisel is:

[info] [0.001] Elaborating design...
[error] chisel3.internal.ChiselException: Connection between sink (chisel3.core.UInt@1b206824) and source (chisel3.core.SInt@511647f3)
failed @: Sink (chisel3.core.UInt@1b206824) and Source (chisel3.core.SInt@511647f3) have different types.
[error]         ...
[error]         at dinocpu.SingleCycleCPU.<init>(cpu.scala:33)
[error]         at dinocpu.CPUConfig.getCPU(configuration.scala:30)
[error]         at dinocpu.Top.$anonfun$cpu$1(top.scala:14)
[error]         at chisel3.core.Module$.do_apply(Module.scala:51)
[error]         at dinocpu.Top.<init>(top.scala:14)
[error]         at dinocpu.simulate$.$anonfun$build$1(simulate.scala:80)
[error]         ... (Stack trace trimmed to user code only, rerun with --full-stacktrace if you wish to see the full stack trace)
[info] SingleCycleAddTesterLab1:
[info] Single Cycle CPU
[info] - should run add test add1 *** FAILED ***
[info]   java.lang.Exception: Problem with compilation
[info]   at dinocpu.simulate$.build(simulate.scala:89)
[info]   at dinocpu.CPUTesterDriver.<init>(CPUTesterDriver.scala:24)
[info]   at dinocpu.CPUTesterDriver$.apply(CPUTesterDriver.scala:108)
[info]   at dinocpu.SingleCycleAddTesterLab1.$anonfun$new$6(Lab1Test.scala:77)
[info]   at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info]   at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[info]   at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info]   at org.scalatest.Transformer.apply(Transformer.scala:22)
[info]   at org.scalatest.Transformer.apply(Transformer.scala:20)
[info]   at org.scalatest.FlatSpecLike$$anon$1.apply(FlatSpecLike.scala:1682)

The important part to notice is the following:

[error] chisel3.internal.ChiselException: Connection between sink (chisel3.core.UInt@1b206824) and source (chisel3.core.SInt@511647f3)
failed @: Sink (chisel3.core.UInt@1b206824) and Source (chisel3.core.SInt@511647f3) have different types.

This says the source and sink (input and output) types don’t match. In other words, one is signed and one is unsigned.

As a general hint, look at the highest error in the output, or the error that’s generated first, not the error at the bottom.