Picolib support

Makefile

@@ -14,7 +14,7 @@ endif
 CORE_LIST=$(patsubst riscv/%,%,$(wildcard riscv/*))
 PE_LIST=$(addsuffix _pe, $(CORE_LIST))
 
-all: $(PE_LIST)
+all: $(PE_LIST) picolibc
 
 list:
 	@echo $(CORE_LIST)
@@ -27,8 +27,16 @@ list:
 %_setup: riscv/%/setup.sh
 	$<
 
+picolibc: picolibc_support/build_picolibc.sh
+	picolibc_support/build_picolibc.sh $(PICOLIBC_OPTS)
+
 uninstall:
 	rm -rf $(TAPASCO_HOME)/core/{${PE_LIST}}*
 
-clean: uninstall
+clean_picolib:
+	rm -rf picolibc_support/picolibc
+	rm -rf picolibc_support/picolibc-git
+	rm -rf picolibc_support/specs
+
+clean: uninstall clean_picolib
 	rm -rf IP/riscv/

README.md

@@ -13,6 +13,8 @@ The folder **common** contains TCL scripts which place and connect common compon
 
 The folder **specific_tcl** contains one TCL script per processor and places/connects the components which depend on the chosen processor, e.g. instantiate the correct IP and connect the memory busses.
 
+The folder **picolibc_support** contains a script as well as an adjusted linker script and code for stdio support to build the [picolibc](https://github.com/picolibc/picolibc) for the RISC-V cores.
+
 ## Dependencies
 The project might work with other configurations, but it was tested with the following setup:
 * Vivado 2018.3
@@ -67,5 +69,31 @@ e.g. BRAM_SIZE=0x4000 makes a local memory size of 0x8000.
 
 For more information on PE local memory please refer to the [documentation](https://github.com/esa-tu-darmstadt/tapasco/blob/master/documentation/pe-local-memories.md).
 
+## Picolibc Support
+For a better programming experience, you may use the [picolibc](https://github.com/picolibc/picolibc) which provides C standard library functions and standard input/output. The build of picolibc requires the meson build tool which you may install with:
+
+```
+apt install meson
+```
+
+To build the library, just use the built-in script by calling:
+
+```
+make picolibc
+```
+
+You can customize the build of picolibc and specify additional build options by providing the PICOLIBC_OPTS parameter, e.g.:
+
+```
+make PICOLIBC_OPTS="-Dio-long-long=true"
+```
+
+Detailed information about the available build options can be found [here](https://github.com/picolibc/picolibc/blob/main/doc/build.md), however, only the default configuration is tested.
+
+Picolibc provides a specs-file for the GCC you need to specify when compiling software using the standard library.
+
+### Stdin/stdout
+If you would like to use functions like printf, scanf etc. you need to provide memory buffers using the TaPaSCo API, one buffer for stdin and one for stdout/stderr. We provide a header file which helps you with that, take a look at our [programming example](https://github.com/esa-tu-darmstadt/tapasco-riscv/tree/picolib_support/programming/examples/picolibc_example) to find out how to use it.
+
 ## Publications
 Heinz, C., Lavan, Y., Hofmann, J., and Koch, A. (2019). A Catalog and In-Hardware Evaluation of Open-Source Drop-In Compatible RISC-V Softcore Processors. In *IEEE Proc. International Conference on ReConFigurable Computing and FPGAs (ReConFig)*. IEEE. 

picolibc_support/build_picolibc.sh

@@ -0,0 +1,62 @@
+#!/bin/bash
+
+export REPO_ROOT=$(pwd)
+cd picolibc_support
+git clone https://github.com/picolibc/picolibc.git picolibc-git
+
+## include own iob lib for printf support in picolibc meson build
+cp -r tapasco_iob picolibc-git
+sed -i "/subdir('semihost')/a subdir('tapasco_iob')" picolibc-git/meson.build
+
+cd picolibc-git
+mkdir -p build
+
+## replace picolibc linker script with own adjusted linker script
+## because data sections need to be place immediately to data memory (ram section)
+for file in $(find . -name "picolibc.ld")
+do
+	cp $REPO_ROOT/picolibc_support/linker_script/picolibc_adjusted.ld $file
+done
+
+## delete memcpy copying the data section from startup code and reference to __data_source since it is not necessary in our case
+for file in $(find . -name "crt0.h")
+do
+	sed -i '/data_source/d' $file
+done
+
+## add link forown iob library for printf support
+for file in $(find . -name "picolibc.specs.in")
+do
+	sed -i "s:--end-group:-ltapascoiob --end-group:" $file
+done
+
+## find out if riscv32 or riscv64 GCC must be used
+if command -v riscv64-unknown-elf-gcc &> /dev/null
+then
+	echo "Using RISC-V 64-bit GCC"
+	cd build
+	# disable tests to prevent failing build with self built compiler
+	../scripts/do-configure riscv64-unknown-elf -Dtests=false -Dprefix=$REPO_ROOT/picolibc_support -Dspecsdir=specs $1
+	ninja install
+elif command -v riscv32-unknown-elf-gcc &> /dev/null
+then
+	echo "Using RISC-V 32-bit GCC"
+	cd scripts
+	cp cross-riscv64-unknown-elf.txt cross-riscv32-unknown-elf.txt
+	sed -i 's/riscv64/riscv32/' cross-riscv32-unknown-elf.txt
+	cd ../build
+	../scripts/do-configure riscv32-unknown-elf -Dtests=false -Dprefix=$REPO_ROOT/picolibc_support -Dspecsdir=specs $1
+	ninja install
+else
+	echo "No RISC-V compiler found...exiting"
+	exit
+fi
+
+## remove git folder
+cd $REPO_ROOT/picolibc_support
+rm -rf picolibc-git
+
+exit
+
+
+

picolibc_support/linker_script/picolibc_adjusted.ld

@@ -0,0 +1,241 @@
+/*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ * Copyright © 2019 Keith Packard
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above
+ *    copyright notice, this list of conditions and the following
+ *    disclaimer in the documentation and/or other materials provided
+ *    with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its
+ *    contributors may be used to endorse or promote products derived
+ *    from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+ENTRY(_start)
+
+/*
+ * These values should be provided by the application. We'll include
+ * some phony values here to make things link for testing
+ */
+
+MEMORY
+{
+	flash (xai!rw) : ORIGIN = DEFINED(__flash) ? __flash : 0x10000000, LENGTH = DEFINED(__flash_size) ? __flash_size : 0x10000
+	ram (wari!x)   : ORIGIN = DEFINED(__ram  ) ? __ram   : 0x20000000, LENGTH = DEFINED(__ram_size  ) ? __ram_size   : 0x08000
+}
+
+PHDRS
+{
+	text PT_LOAD;
+	ram PT_LOAD;
+	ram_init PT_LOAD;
+	tls PT_TLS;
+}
+
+SECTIONS
+{
+	PROVIDE(__stack = ORIGIN(ram) + LENGTH(ram));
+
+	.init : {
+		KEEP (*(.text.init.enter))
+		KEEP (*(SORT_BY_NAME(.init) SORT_BY_NAME(.init.*)))
+	} >flash AT>flash :text
+
+	.text : {
+		*(.text.unlikely .text.unlikely.*)
+		*(.text.startup .text.startup.*)
+		*(.text .text.*)
+		*(.gnu.linkonce.t.*)
+	} >flash AT>flash :text
+
+	.fini : {
+		KEEP (*(.fini))
+		__text_end = .;
+	} >flash AT>flash :text
+
+	PROVIDE (__etext = __text_end);
+	PROVIDE (_etext = __text_end);
+	PROVIDE (etext = __text_end);
+
+	. = ALIGN(8);
+
+	/* --------------------------------------------------
+	 * start of sections placed in data memory
+	 * --------------------------------------------------
+	 */
+
+
+	/* the following sections contain function pointers instead of actual code!
+	 * so that these function pointers can be read from memory by lw instructions
+	 * they need to be placed in the data memory as well!
+	 */
+	.preinit_array : {
+		PROVIDE_HIDDEN ( __preinit_array_start = . );
+		KEEP (*(.preinit_array))
+		PROVIDE_HIDDEN ( __preinit_array_end = . );
+	} >ram AT>ram :ram
+
+	.init_array : {
+		PROVIDE_HIDDEN ( __init_array_start = . );
+		KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*) SORT_BY_INIT_PRIORITY(.ctors.*)))
+		KEEP (*(.init_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .ctors))
+		PROVIDE_HIDDEN ( __init_array_end = . );
+	} >ram AT>ram :ram
+
+	.fini_array : {
+		PROVIDE_HIDDEN ( __fini_array_start = . );
+		KEEP (*(SORT_BY_INIT_PRIORITY(.fini_array.*) SORT_BY_INIT_PRIORITY(.dtors.*)))
+		KEEP (*(.fini_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .dtors))
+		PROVIDE_HIDDEN ( __fini_array_end = . );
+	} >ram AT>ram :ram
+
+	.ctors : {
+		KEEP (*crtbegin.o(.ctors))
+		KEEP (*crtbegin?.o(.ctors))
+		KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .ctors))
+		KEEP (*(SORT_BY_INIT_PRIORITY(.ctors.*)))
+		KEEP (*(.ctors))
+	} >ram AT>ram :ram
+
+	.dtors : {
+		KEEP (*crtbegin.o(.dtors))
+		KEEP (*crtbegin?.o(.dtors))
+		KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .dtors))
+		KEEP (*(SORT_BY_INIT_PRIORITY(.dtors.*)))
+		KEEP (*(.dtors))
+	} >ram AT>ram :ram
+
+	.data.init.enter : {
+		KEEP (*(.data.init.enter))
+	} >ram AT>ram :ram
+
+	.rodata : {
+		*(.rdata)
+		*(.rodata .rodata.*)
+		*(.gnu.linkonce.r.*)
+		. = ALIGN(8);
+		*(.srodata.cst16)
+		*(.srodata.cst8)
+		*(.srodata.cst4)
+		*(.srodata.cst2)
+		*(.srodata .srodata.*)
+		*(.data.rel.ro .data.rel.ro.*)
+		*(.got .got.*)
+	} >ram AT>ram :ram
+
+	.data : ALIGN_WITH_INPUT {
+		PROVIDE(__data_start = .);
+		*(.data .data.*)
+		*(.gnu.linkonce.d.*)
+ 		. = ALIGN(8);
+		PROVIDE( __global_pointer$ = . + 0x800 );
+		*(.sdata .sdata.* .sdata2.*)
+		*(.gnu.linkonce.s.*)
+	} >ram AT>ram :ram
+
+	/* Thread local initialized data. This gets
+	 * space allocated as it is expected to be placed
+	 * in ram to be used as a template for TLS data blocks
+	 * allocated at runtime. We're slightly abusing that
+	 * by placing the data in flash where it will be copied
+	 * into the allocate ram addresses by the existing
+	 * data initialization code in crt0
+	 */
+	.tdata : ALIGN_WITH_INPUT {
+		PROVIDE( __tls_base = .);
+		*(.tdata .tdata.* .gnu.linkonce.td.*)
+		PROVIDE(__data_end = .);
+	} >ram AT>ram :tls :ram
+	PROVIDE( __tdata_size = SIZEOF(.tdata) );
+
+	PROVIDE( __edata = __data_end );
+	PROVIDE( _edata = __data_end );
+	PROVIDE( edata = __data_end );
+	PROVIDE( __data_size = __data_end - __data_start );
+
+	/*
+	 * Data values which are preserved across reset
+	 */
+	.preserve (NOLOAD) : {
+		PROVIDE(__preserve_start__ = .);
+		KEEP(*(SORT_BY_NAME(.preserve.*)))
+		KEEP(*(.preserve))
+		PROVIDE(__preserve_end__ = .);
+	} >ram AT>ram :ram
+
+
+
+	.tbss (NOLOAD) : {
+		PROVIDE( __bss_start = . );
+		*(.tbss .tbss.* .gnu.linkonce.tb.*)
+		*(.tcommon)
+		PROVIDE( __tls_end = . );
+	} >ram AT>ram :tls :ram
+	PROVIDE( __tbss_size = SIZEOF(.tbss) );
+	PROVIDE( __tls_size = __tls_end - __tls_base );
+
+	/*
+	 * The linker special cases .tbss segments which are
+	 * identified as segments which are not loaded and are
+	 * thread_local.
+	 *
+	 * For these segments, the linker does not advance 'dot'
+	 * across them.  We actually need memory allocated for tbss,
+	 * so we create a special segment here just to make room
+	 */
+	.tbss_space (NOLOAD) : {
+		. = . + __tbss_size;
+	} >ram AT>ram :ram
+
+	.bss (NOLOAD) : {
+		*(.sbss*)
+		*(.gnu.linkonce.sb.*)
+		*(.bss .bss.*)
+		*(.gnu.linkonce.b.*)
+		*(COMMON)
+		. = ALIGN(8);
+		__bss_end = .;
+	} >ram AT>ram :ram
+	PROVIDE( __end = __bss_end );
+	PROVIDE( _end = __bss_end );
+	PROVIDE( end = __bss_end );
+	PROVIDE( __bss_size = __bss_end - __bss_start );
+
+	/* Make the rest of memory available for heap storage */
+	PROVIDE (__heap_start = __end);
+	PROVIDE (__heap_end = __stack - (DEFINED(__stack_size) ? __stack_size : 0x800));
+	PROVIDE (__heap_size = __heap_end - __heap_start);
+
+	/* Define a stack region to make sure it fits in memory */
+	.stack __heap_end (NOLOAD) : {
+		. += (DEFINED(__stack_size) ? __stack_size : 0x800);
+	} >ram :ram
+
+	/* Throw away C++ exception handling information */
+	/DISCARD/ : {
+		*(.eh_frame .eh_frame.*)
+		*(.note .note.*)
+	}
+}