我的目标是模拟运行裸机软件的Zynq-7000上的ARM A9处理器。我已经尝试了两种不同的方法来解决这两个问题。有关如何进行的任何建议将不胜感激。
链接到Linux Kernel Module Cheat（LKMC，使用v3.0）使用./build --arch arm qemu-baremetal构建
使用ARM虚拟机（-virt标志）的站点上的示例正常工作。尝试修改此设置以使其适合我的设置是导致问题的原因（以下详细信息）。
我试图复制示例命令行调用，但是使用-cpu cortex-a9选项：qemu-system-arm: mach-virt: CPU cortex-a9 not supported然后我将整个调用更改为qemu-system-arm -M xilinx-zynq-a9 -cpu cortex-a9 -nographic -kernel hello.elf -m 512M -serial mon:stdio -s -S它因错误而崩溃qemu: fatal: Trying to execute code outside RAM or ROM at 0x40000000这是有道理的，因为该应用程序是使用LKMC构建的，而我试图在该框架之外运行它。
因此，我尝试运行自己的应用程序，该应用程序是使用Xilinx工具链的修改版进行编译的。我确信它不会立即生效，因为启动顺序中的某些部分我必须更改。但是我试图弄清楚它们是什么并进行更改。与运行qemu-system-arm -M xilinx-zynq-a9 -cpu cortex-a9 -nographic -kernel helloworld.elf -m 512M -serial mon:stdio -s -S允许GDB成功连接，但无法正确读取符号表。使用arm-none-eabi-objdump -D helloworld.elf告诉我main位于0x001004fc，但是GDB认为它位于0x40000324（使用命令info address main）。
PYNQ-Z1（webpage，datasheet）具有32位ARM Cortex-A9处理器，因此这就是为什么我使用qemu-system-arm而不是qemu-system-aarch64的原因。如果那是错误的，有人可以纠正我。
注意，我不能简单地切换到其他体系结构；我使用的代码无法容忍更改，除了进行细微调整外，不能使板级支持软件包（BSP）与模拟器兼容，而不会损害我的研究的有效性。
我已经离开了一段时间了./run --arch arm -m 512M --baremetal pynq/helloworld --wait-gdb./run-gdb --arch arm --baremetal pynq/helloworld --no-continue -- main然后我逐步使用GDB查找哪里有数据中止，并找出Qemu不支持哪种硬件。
我正在运行的软件是使用经过修改的Xilinx工具链构建的，因此包含许多Xilinx标准库功能。到目前为止，在修改代码以使其与虚拟机一起使用时，我发现了一些更改，例如更改UART设备的地址以及禁用一些启动任务，例如使SCU无效或更改缓存控制器配置，这可能是因为这些东西不是Qemu模仿的。
[调试启动时，启动时遇到的下一个问题是XTime函数（xtime_l.c）。这些功能是读取全局系统计时器的包装器。 Qemu界面中命令info mtree的结果似乎表明没有与之交互的全局计时器设备。是否可以将计时器设备添加到ARM虚拟机？只要使用与寄存器读取和写入相同的方式在Zynq上使用它，基址是什么都无所谓。
然后我尝试使用特定的机器标志xilinx-zynq-a9。 LKMC生成以下命令：
+ /home/$USER/$INSTALL_DIR/out/qemu/default/arm-softmmu/qemu-system-arm \
-machine xilinx-zynq-a9 \
-gdb tcp::45457 \
-kernel /home/$USER/$INSTALL_DIR/out/baremetal/arm/qemu/xilinx-zynq-a9/hello.elf \
-m 512M \
-monitor telnet::45454,server,nowait \
-netdev user,hostfwd=tcp::45455-:45455,hostfwd=tcp::45456-:22,id=net0 \
-no-reboot \
-smp 1 \
-virtfs local,path=/home/$USER/$INSTALL_DIR/data/9p,mount_tag=host_data,security_model=mapped,id=host_data \
-virtfs local,path=/home/$USER/$INSTALL_DIR/out,mount_tag=host_out,security_model=mapped,id=host_out \
-virtfs local,path=/home/$USER/$INSTALL_DIR/rootfs_overlay,mount_tag=host_rootfs_overlay,security_model=mapped,id=host_rootfs_overlay \
-serial mon:stdio \
-trace enable=load_file,file=/home/$USER/$INSTALL_DIR/out/run/qemu/arm/0/trace.bin \
-cpu cortex-a9 \
-device virtio-gpu-pci \
-nographic \
-serial tcp::45458,server,nowait \
-semihosting \
;
此虚拟机与通用虚拟机之间的唯一区别是指定计算机和cpu的行，它们分别是-machine virt -machine highmem=off和-cpu cortex-a15（我实际上不得不修改LKMC代码以使其输出。机器的正确CPU名称）。
但是，此操作因错误而失败qemu-system-arm: -device rtl8139,netdev=net0: No 'PCI' bus found for device 'rtl8139'这是有道理的，因为并非所有Zynq部件都具有PCI总线。因此，大多数情况下，我想知道为什么当目标仍然是裸机时，LKMC为什么会生成这样的命令序列。
我认为第一种选择最有可能起作用，因为-virt机器似乎比某些特定目标有更好的支持。有趣的是，Xilinx SDK附带的Qemu版本不支持Zynq的裸机（在Xilinx Docs中称为“独立”）。
是否可以将计时器设备添加到ARM虚拟机？有人在Qemu Xilinx ARM A9上运行裸机代码吗？
我已尝试尽可能具体，但随时可以提出澄清的问题。
Global
Timer Counter的1448页描述的Zynq-7000 Technical
Reference Manual。请注意，为了回答您的问题，我改编了我已经可用的并且已经知道正在工作的现有个人项目。
[Building QEMU：execute build-qemu.sh-此脚本可在64位Ubuntu 18.04和19.10上运行，您必须将PERL_MODULES_VERSION设置为5.28。
build-qemu.sh：
#!/bin/bash
set -e
QEMU_VERSION=4.2.0
# xenial
PERL_MODULES_VERSION=5.22
# eoan
PERL_MODULES_VERSION=5.28
# bionic
PERL_MODULES_VERSION=5.26
PREFIX=/opt/qemu-${QEMU_VERSION}
do_install_prerequisites()
{
sudo apt-get install libglib2.0-dev libfdt-dev libpixman-1-dev zlib1g-dev libaio-dev libbluetooth-dev libbrlapi-dev libbz2-dev libcap-dev libcap-ng-dev libcurl4-gnutls-dev libgtk-3-dev libibverbs-dev \
libjpeg8-dev libncurses5-dev libnuma-dev librbd-dev librdmacm-dev libsasl2-dev libsdl2-dev libseccomp-dev libsnappy-dev libssh2-1-dev libvde-dev libvdeplug-dev libvte-2.91-dev libxen-dev liblzo2-dev \
valgrind xfslibs-dev liblzma-dev flex bison texinfo perl perl-modules-${PERL_MODULES_VERSION} python-sphinx gettext
}
do_download_qemu()
{
if [ ! -f qemu-${QEMU_VERSION}.tar.xz ]
then
wget https://download.qemu.org/qemu-${QEMU_VERSION}.tar.xz
fi
}
do_extract_qemu()
{
echo "extracting..."
rm -rf qemu-${QEMU_VERSION}
tar Jxf qemu-${QEMU_VERSION}.tar.xz
}
do_configure_qemu()
{
local TARGET_LIST="arm-softmmu"
pushd qemu-${QEMU_VERSION}
./configure --target-list="${TARGET_LIST}" --prefix=${PREFIX} --extra-cflags="-I$(pwd)/packages/include" --extra-ldflags="-L$(pwd)/packages/lib"
popd
}
do_build_qemu()
{
echo "building..."
pushd qemu-${QEMU_VERSION}
make all
popd
}
do_install_qemu()
{
echo "installing..."
pushd qemu-${QEMU_VERSION}
sudo make install
popd
}
do_build()
{
do_download_qemu
do_extract_qemu
do_configure_qemu
do_build_qemu
do_install_qemu
}
# main
do_install_prerequisites
do_build
在脚本完成时，您应该已安装qemu-system-user 4.2.0：
ls -gG /opt/qemu-4.2.0/bin/
total 22992
-rwxr-xr-x 1 22520 Feb 21 23:57 elf2dmp
-rwxr-xr-x 1 18424 Feb 21 23:57 ivshmem-client
-rwxr-xr-x 1 218264 Feb 21 23:57 ivshmem-server
-rwxr-xr-x 1 30864 Feb 21 23:57 qemu-edid
-rwxr-xr-x 1 374328 Feb 21 23:57 qemu-ga
-rwxr-xr-x 1 1767744 Feb 21 23:57 qemu-img
-rwxr-xr-x 1 1719104 Feb 21 23:57 qemu-io
-rwxr-xr-x 1 505016 Feb 21 23:57 qemu-keymap
-rwxr-xr-x 1 1727744 Feb 21 23:57 qemu-nbd
-rwxr-xr-x 1 599848 Feb 21 23:57 qemu-pr-helper
-rwxr-xr-x 1 16510840 Feb 21 23:57 qemu-system-arm
-rwxr-xr-x 1 26856 Feb 21 23:57 virtfs-proxy-helper
我们现在需要创建以下文件：
gcc_arm32_ram.ld（根据标准GCC CMSIS 5.60 linker script改编：
/******************************************************************************
* @file gcc_arm32.ld
* @brief GNU Linker Script for Cortex-M based device
* @version V2.0.0
* @date 21. May 2019
******************************************************************************/
/*
* Copyright (c) 2009-2019 Arm Limited. All rights reserved.
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the License); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an AS IS BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
MEMORY
{
RAM (rwx) : ORIGIN = __RAM_BASE, LENGTH = __RAM_SIZE
}
/* Linker script to place sections and symbol values. Should be used together
* with other linker script that defines memory regions FLASH and RAM.
* It references following symbols, which must be defined in code:
* Reset_Handler : Entry of reset handler
*
* It defines following symbols, which code can use without definition:
* __exidx_start
* __exidx_end
* __copy_table_start__
* __copy_table_end__
* __zero_table_start__
* __zero_table_end__
* __etext
* __data_start__
* __preinit_array_start
* __preinit_array_end
* __init_array_start
* __init_array_end
* __fini_array_start
* __fini_array_end
* __data_end__
* __bss_start__
* __bss_end__
* __end__
* end
* __HeapLimit
* __StackLimit
* __StackTop
* __stack
*/
ENTRY(Reset_Handler)
SECTIONS
{
.text :
{
KEEP(*(.vectors))
*(.text*)
KEEP(*(.init))
KEEP(*(.fini))
/* .ctors */
*crtbegin.o(.ctors)
*crtbegin?.o(.ctors)
*(EXCLUDE_FILE(*crtend?.o *crtend.o) .ctors)
*(SORT(.ctors.*))
*(.ctors)
/* .dtors */
*crtbegin.o(.dtors)
*crtbegin?.o(.dtors)
*(EXCLUDE_FILE(*crtend?.o *crtend.o) .dtors)
*(SORT(.dtors.*))
*(.dtors)
*(.rodata*)
KEEP(*(.eh_frame*))
} > RAM
/*
* SG veneers:
* All SG veneers are placed in the special output section .gnu.sgstubs. Its start address
* must be set, either with the command line option �--section-start� or in a linker script,
* to indicate where to place these veneers in memory.
*/
/*
.gnu.sgstubs :
{
. = ALIGN(32);
} > RAM
*/
.ARM.extab :
{
*(.ARM.extab* .gnu.linkonce.armextab.*)
} > RAM
__exidx_start = .;
.ARM.exidx :
{
*(.ARM.exidx* .gnu.linkonce.armexidx.*)
} > RAM
__exidx_end = .;
.copy.table :
{
. = ALIGN(4);
__copy_table_start__ = .;
LONG (__etext)
LONG (__data_start__)
LONG (__data_end__ - __data_start__)
/* Add each additional data section here */
/*
LONG (__etext2)
LONG (__data2_start__)
LONG (__data2_end__ - __data2_start__)
*/
__copy_table_end__ = .;
} > RAM
.zero.table :
{
. = ALIGN(4);
__zero_table_start__ = .;
/* Add each additional bss section here */
/*
LONG (__bss2_start__)
LONG (__bss2_end__ - __bss2_start__)
*/
__zero_table_end__ = .;
} > RAM
/**
* Location counter can end up 2byte aligned with narrow Thumb code but
* __etext is assumed by startup code to be the LMA of a section in RAM
* which must be 4byte aligned
*/
__etext = ALIGN (4);
.data : AT (__etext)
{
__data_start__ = .;
*(vtable)
*(.data)
*(.data.*)
. = ALIGN(4);
/* preinit data */
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP(*(.preinit_array))
PROVIDE_HIDDEN (__preinit_array_end = .);
. = ALIGN(4);
/* init data */
PROVIDE_HIDDEN (__init_array_start = .);
KEEP(*(SORT(.init_array.*)))
KEEP(*(.init_array))
PROVIDE_HIDDEN (__init_array_end = .);
. = ALIGN(4);
/* finit data */
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP(*(SORT(.fini_array.*)))
KEEP(*(.fini_array))
PROVIDE_HIDDEN (__fini_array_end = .);
KEEP(*(.jcr*))
. = ALIGN(4);
/* All data end */
__data_end__ = .;
} > RAM
/*
* Secondary data section, optional
*
* Remember to add each additional data section
* to the .copy.table above to asure proper
* initialization during startup.
*/
/*
__etext2 = ALIGN (4);
.data2 : AT (__etext2)
{
. = ALIGN(4);
__data2_start__ = .;
*(.data2)
*(.data2.*)
. = ALIGN(4);
__data2_end__ = .;
} > RAM2
*/
.bss :
{
. = ALIGN(4);
__bss_start__ = .;
*(.bss)
*(.bss.*)
*(COMMON)
. = ALIGN(4);
__bss_end__ = .;
} > RAM AT > RAM
/*
* Secondary bss section, optional
*
* Remember to add each additional bss section
* to the .zero.table above to asure proper
* initialization during startup.
*/
/*
.bss2 :
{
. = ALIGN(4);
__bss2_start__ = .;
*(.bss2)
*(.bss2.*)
. = ALIGN(4);
__bss2_end__ = .;
} > RAM2 AT > RAM2
*/
.heap (COPY) :
{
. = ALIGN(8);
__end__ = .;
PROVIDE(end = .);
. = . + __HEAP_SIZE;
. = ALIGN(8);
__HeapLimit = .;
} > RAM
.stack (ORIGIN(RAM) + LENGTH(RAM) - __STACK_SIZE) (COPY) :
{
. = ALIGN(8);
__StackLimit = .;
. = . + __STACK_SIZE;
. = ALIGN(8);
__StackTop = .;
} > RAM
PROVIDE(__stack = __StackTop);
/* Check if data + heap + stack exceeds RAM limit */
ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed with stack")
}
Makefile.inc
# Shared Makefile
.PHONY: clean
all: $(MACHINE).elf
$(MACHINE).elf: $(SOURCES) $(MACHINE).c
$(CC) $(CFLAGS) $(LDFLAGS) -o $(MACHINE).elf $(MACHINE).c $(SOURCES)
$(OBJDUMP) -d $(MACHINE).elf > $(MACHINE).lst
qemu: $(MACHINE).elf
$(QEMU_SYSTEM) -m 513M -nographic -machine $(MACHINE) $(QEMU_DEBUG_OPTIONS) -cpu $(CPU) -kernel $(MACHINE).elf
gdb: $(MACHINE).elf
$(GDB) --quiet --command=$(GDB_COMMANDS) $(MACHINE).elf
clean:
rm -f $(MACHINE).elf $(MACHINE).lst
startup-aarch32.s：
.title startup-aarch32.s
.arch armv7-a
.text
.section .text.startup,"ax"
.globl Reset_Handler
Reset_Handler:
ldr r0, =__StackTop
mov sp, r0
bl start
wait: wfe
b wait
.end
xilinx-zynq-a9.c：
#include <stdint.h>
/* Reference: https://www.xilinx.com/support/documentation/user_guides/ug585-Zynq-7000-TRM.pdf - page 1449.
1. Read the upper 32-bit timer counter register
2. Read the lower 32-bit timer counter register
3. Read the upper 32-bit timer counter register again.
If the value is different to the32-bit upper value read previously, go back to step 2.
Otherwise the 64-bit timercounter value is correct.
*/
static const uintptr_t Global_Timer_Counter_Register0 = 0xF8F00200;
static const uintptr_t Global_Timer_Counter_Register1 = 0xF8F00204;
void start()
{
uint64_t global_timer_counter = 0;
uint32_t upper = 0;
uint32_t upper2 = 0;
uint32_t lower = 0;
for (;;) {
upper = *(volatile uint32_t*) Global_Timer_Counter_Register1;
lower = *(volatile uint32_t*) Global_Timer_Counter_Register0;
upper2 = *(volatile uint32_t*) Global_Timer_Counter_Register1;
if (upper != upper2) {
lower = *(volatile uint32_t*) Global_Timer_Counter_Register0;
}
global_timer_counter = (uint64_t) upper << 32 | lower;
}
}
xilinx-zynq-a9.gdb：
target remote localhost:1234
monitor reset halt
load
break Reset_Handler
break start
xilinx-zynq-a9.ld：
/*
*-------- <<< Use Configuration Wizard in Context Menu >>> -------------------
*/
/*--------------------- Embedded RAM Configuration ----------------------------
<h> RAM Configuration
<o0> RAM Base Address <0x0-0xFFFFFFFF:8>
<o1> RAM Size (in Bytes) <0x0-0xFFFFFFFF:8>
</h>
-----------------------------------------------------------------------------*/
__RAM_BASE = 0x00100000;
__RAM_SIZE = 0x20000000;
/*--------------------- Stack / Heap Configuration ----------------------------
<h> Stack / Heap Configuration
<o0> Stack Size (in Bytes) <0x0-0xFFFFFFFF:8>
<o1> Heap Size (in Bytes) <0x0-0xFFFFFFFF:8>
</h>
-----------------------------------------------------------------------------*/
__STACK_SIZE = 0x00020000;
__HEAP_SIZE = 0x00080000;
/*
*-------------------- <<< end of configuration section >>> -------------------
*/
INCLUDE gcc_arm32_ram.ld
我指定了一个从0x20000000开始的512MiB DDR RAM区域-有关Zynq-7000 memory map的更多信息，请参见此处。
xilinx-zynq-a9.mak：
# Toolchain
CROSS_COMPILE=/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/arm-none-eabi-
CC=$(CROSS_COMPILE)gcc
OBJDUMP=$(CROSS_COMPILE)objdump
OBJCOPY=$(CROSS_COMPILE)objcopy
# Target
CPU=cortex-a9
MACHINE=xilinx-zynq-a9
CFLAGS=-O0 -ggdb -mtune=$(CPU) -nostdlib -nostartfiles -ffreestanding
LDFLAGS=-L. -Wl,-T,$(MACHINE).ld
SOURCES=startup-aarch32.s
# qemu
QEMU_DEBUG_OPTIONS=-S -gdb tcp::1234,ipv4
QEMU_SYSTEM=/opt/qemu-4.2.0/bin/qemu-system-arm
# GDB
GDB=$(CROSS_COMPILE)gdb
GDB_COMMANDS=${MACHINE}.gdb
include Makefile.inc
您现在需要安装latest GCC toolchain provided by arm：
wget "https://developer.arm.com/-/media/Files/downloads/gnu-a/9.2-2019.12/binrel/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi.tar.xz?revision=64186c5d-b471-4c97-a8f5-b1b300d6594a&la=en&hash=5E9204DA5AF0B055B5B0F50C53E185FAA10FF625" -o gcc-arm-9.2-2019.12-x86_64-arm-none-eabi.tar.xz
mkdir -p /opt/arm/9
tar Jxf gcc-arm-9.2-2019.12-x86_64-arm-none-eabi.tar.xz -C /opt/arm/9
您现在准备编译/执行/调试示例：
make -f xilinx-zynq-a9.mak clean all
您应该获得以下输出：
rm -f xilinx-zynq-a9.elf xilinx-zynq-a9.lst
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/arm-none-eabi-gcc -O0 -ggdb -mtune=cortex-a9 -nostdlib -nostartfiles -ffreestanding -L. -Wl,-T,xilinx-zynq-a9.ld -o xilinx-zynq-a9.elf xilinx-zynq-a9.c startup-aarch32.s
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/arm-none-eabi-objdump -d xilinx-zynq-a9.elf > xilinx-zynq-a9.lst
您可以启动QEMU：
make -f xilinx-zynq-a9.mak qemu
应该显示已执行的QEMU命令：
/opt/qemu-4.2.0/bin/qemu-system-arm -m 513M -nographic -machine xilinx-zynq-a9 -S -gdb tcp::1234,ipv4 -cpu cortex-a9 -kernel xilinx-zynq-a9.elf
在另一个shell中，启动GDB：
make -f xilinx-zynq-a9.mak gdb
您应该看到以下输出：
/opt/arm/9/gcc-arm-9.2-2019.12-x86_64-arm-none-eabi/bin/arm-none-eabi-gdb --quiet --command=xilinx-zynq-a9.gdb xilinx-zynq-a9.elf
Reading symbols from xilinx-zynq-a9.elf...
Reset_Handler () at startup-aarch32.s:7
7 ldr r0, =__StackTop
unknown command: 'reset'
Loading section .text, size 0xd8 lma 0x100000
Loading section .copy.table, size 0xc lma 0x1000d8
Start address 0x1000b8, load size 228
Transfer rate: 222 KB/sec, 114 bytes/write.
Breakpoint 1 at 0x1000b8: file startup-aarch32.s, line 7.
Breakpoint 2 at 0x10000c: file xilinx-zynq-a9.c, line 17.
(gdb)
执行continue：
(gdb) continue
Continuing.
Breakpoint 2, start () at xilinx-zynq-a9.c:17
17 uint64_t global_timer_counter = 0;
现在，执行几个step命令，并在每行显示global_timer_counter变量：
31 global_timer_counter = (uint64_t) upper << 32 | lower;
已执行：
(gdb) p/x global_timer_counter
$2 = 0xa6f2a0a
(gdb) p/x global_timer_counter
$9 = 0xa84315b
(gdb) p/x global_timer_counter
$10 = 0xabe77cf
64位变量不断增加¸，这与QEMU对Zynq全局计时器计数器的有效仿真一致，并且我们现在有了可以使用GDB调试的有效的裸机Zynq-7000示例。
我希望我回答了你问的两个问题。