From 7f5d8c8dba9600a3ab47fae955802c1cf8c96290 Mon Sep 17 00:00:00 2001 From: David Biancolin Date: Wed, 24 Feb 2021 13:05:14 -0800 Subject: [PATCH] Update frequency selection related comments --- generators/firechip/src/main/scala/TargetConfigs.scala | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/generators/firechip/src/main/scala/TargetConfigs.scala b/generators/firechip/src/main/scala/TargetConfigs.scala index 92cd02c3d3..ece2546bd2 100644 --- a/generators/firechip/src/main/scala/TargetConfigs.scala +++ b/generators/firechip/src/main/scala/TargetConfigs.scala @@ -68,8 +68,10 @@ class WithFireSimConfigTweaks extends Config( new WithFireSimSimpleClocks ++ // Required*: When using FireSim-as-top to provide a correct path to the target bootrom source new WithBootROM ++ - // Optional*: Removing this will require adjusting the UART baud rate and - // potential target-software changes to properly capture UART output + // Optional: This sets the default frequency for all buses in the system to 3.2 GHz + // (since unspecified bus frequencies will use the pbus frequency) + // This frequency selection matches FireSim's legacy selection and is required + // to support 200Gb NIC performance. You may select a smaller value. new chipyard.config.WithPeripheryBusFrequency(3200.0) ++ // Optional: These three configs put the DRAM memory system in it's own clock domian. // Removing the first config will result in the FASED timing model running @@ -93,7 +95,7 @@ class WithFireSimConfigTweaks extends Config( new testchipip.WithDefaultSerialTL ++ // Optional: Removing this will require using an initramfs under linux new testchipip.WithBlockDevice ++ - // Required*: Scale default baud rate with periphery bus frequency + // Optional: Set a UART baudrate (this selection matches FireSim's historical value) new chipyard.config.WithUART(BigInt(3686400L)) ++ // Required: Do not support debug module w. JTAG until FIRRTL stops emitting @(posedge ~clock) new chipyard.config.WithNoDebug