The REFRESH register accepts an 8-bit address and determines which
register to refresh. Since there are only two addresses currently in
use, this register can be either 0x00 or 0x04.
A refactor replaced the compare with one that checked for any 0 bits.
Since both 0x00 and 0x04 have 0 bits, this check always evaluated as
true, causing the logic to always refresh the CORE register.
Replace this check with an explicit check for 0x00.
Signed-off-by: Sean Cross <sean@xobs.io>
Add the vexriscv_debug program to the list of scripts created when
installing this module. This program is a simple bridge that allows
openocd to talk to the vexriscv core so it can be debugged.
Signed-off-by: Sean Cross <sean@xobs.io>
Enable resetting the UART by adding a ResetInserter to the UART.
The UART must be reset when resetting the softcore.
Signed-off-by: Sean Cross <sean@xobs.io>
Allow a new cpu_debugging flag to be passed to the constructor to
enable in-circuit live debugging of the softcore under gdb.
Signed-off-by: Sean Cross <sean@xobs.io>
Add support for debugging the CPU, and gate it behind a new cpu_debug
parameter. With this enabled, a simple Wishbone interface is provided.
The debug version of the core adds two 32-bit registers to the CPU.
The register at address 0 indicates status, and is used to halt
and reset the core.
The debug register at address 4 is used to inject opcodes into the
core, and read back the result.
A patched version of OpenOCD can be used to attach to this bus via
the Litex Ethernet or UART bridges.
Signed-off-by: Sean Cross <sean@xobs.io>
The upstream vexriscv repo now generates both the current VexRiscv.v
softcore, as well as VexRiscv-Debug.v. This -Debug varient exposes
their specialized debug bus that allows for attaching a modified version
of openocd.
Sync the litex repo with the upstream version to take advantage of debug
support.
Signed-off-by: Sean Cross <sean@xobs.io>
The BIOS builds just fine on Windows, but afterwards tries to run
`chmod`. This command does not exist on Windows, and is unnecessary.
Add a conditional guard to prevent this command from running on Windows.
Signed-off-by: Sean Cross <sean@xobs.io>
Florent Kermarrec
Sean Cross
bunnie
Deano Calver
Dolu1990