清除bss段的代码部分如下： //清除BSS段 clean_bss: ldr r1 =__bss_start ldr r2 =__bss_end mov r3 #0 clean: str r3 [r1] add r1 r1 #4 cmp r1 r2 bne clean复制代码 想问一下大佬，clean部分清除bss段的原理，为啥将r1寄存器清零后，又要加上4，与r2执行了CMP指令，零标志寄存器不为零的话则循环，我自己的理解： R1清零→+4→清零→+4，那这样如何起到清除bss段呢，请大佬指点
linux使用设备树开发驱动，比如我的项目中不需要音频或者四轴传感器，一、是不是只要修改设备树，重新编译设备树再下载到存储器中就可以了呢？若为了减小内核大小，是不是还的进行二操作？ 二、修改好设备树后，还得配置内核，取消内核中的音视频驱动，重新编译内核才行？
Linux驱动开发中，主设备号一致，多个从设备的中断注册函数中的中断号怎么传？比如实现一个杂项设备，主设备号为10，，，其下挂了多个从设备，这时要对多个从设备注册中断处理函数，request_irq()的入参怎么传？
E:\worksapce_Qt\xx.cpp:56: error: constant expression evaluates to 170 which cannot be narrowed to type 'char'这不应该吧。怎么破
有大神在Linux开发板上支持虚拟键盘吗？能分享一下该怎么搞吗？ 我的键盘显示现在显示这样，求解为什么 无标题.png (252.43 KB 下载次数: 0) 下载附件 3 天前 上传
如题，能否将一般的实时操作系统也改成类似于Linux实时态和用户态，然后通过中间的Ioctrl来调用？有熟悉嵌入式操作系统的大神试过没？该怎么实现？结合CPU的异常等级（特权）？如何切换硬件层面的CPU的特权等级？
在AM3358平台移植Uboot（ver=U-Boot 2018.07）以太网可以识别但是ping不通： U-Boot 2018.07 (Feb 28 2021 - 18:59:04 -0800) WJP F:arch/arm/mach-omap2/am33xx/sys_info.cL:130 CPU : AM335X-GP rev 2.1 Model: TI AM335x EVM-SK DRAM: 256 MiB F:common/board_r.cL:423board_init_r start F:common/board_r.cL:423board_init_r end WJP F:board/ti/am335x/board.c L:636 F:board_init start: WJP F:board/ti/am335x/board.c L:718 F:board_init end: F:commooard_r.cL:403NAND: 128 MiB F:commooard_r.cL:423 MMC: OMAP SD/MMC: 0 OMAP SD/MMC: 1 Loading Environment from FAT... Unable to use mmc 0:1... Failed (-5) No USB device found <ethaddr> not set. Validating first E-fuse MAC Net: eth0: ethernet@4a100000 Hit any key to stop autoboot: 0 => setenv ipaddr 172.30.131.12 => setenv serverip 172.30.131.200 => printenv arch=arm args_mmc=run finduuid;setenv bootargs console=${console} ${optargs} root=PARTUUID=${uuid} rw rootfstype=${mmcrootfstype} baudrate=115200 board=am335x boot_a_script=load ${devtype} ${devnum}{distro_bootpart} ${scriptaddr} ${prefix}${script}; source ${scriptaddr} boot_efi_binary=if fdt addr ${fdt_addr_r}; then bootefi bootmgr ${fdt_addr_r};else bootefi bootmgr ${fdtcontroladdr};fi;load ${devtype} ${devnum}{distro_bootpart} ${kernel_addr_r} efi/boot/bootarm.efi; if fdt addr ${fdt_addr_r}; then bootefi ${kernel_addr_r} ${fdt_addr_r};else bootefi ${kernel_addr_r} ${fdtcontroladdr};fi boot_extlinux=sysboot ${devtype} ${devnum}{distro_bootpart} any ${scriptaddr} ${prefix}extlinux/extlinux.conf boot_fdt=try boot_fit=0 boot_net_usb_start=usb start boot_prefixes=/ /boot/ boot_script_dhcp=boot.scr.uimg boot_scripts=boot.scr.uimg boot.scr boot_targets=mmc0 legacy_mmc0 mmc1 legacy_mmc1 nand0 pxe dhcp bootcmd=if test ${boot_fit} -eq 1; then run update_to_fit; fi; run findfdt; run init_console; run envboot; run distro_bootcmd bootcmd_dhcp=run boot_net_usb_start; if dhcp ${scriptaddr} ${boot_script_dhcp}; then source ${scriptaddr}; fi;setenv efi_fdtfile ${fdtfile}; if test -z "${fdtfile}" -a -n "${soc}"; then setenv efi_fdtfile ${soc}-${board}${boardver}.dtb; fi; setenv efi_old_vci ${bootp_vci};setenv efi_old_arch ${bootp_arch};setenv bootp_vci PXEClient:Arch:00010:UNDI:003000;setenv bootp_arch 0xa;if dhcp ${kernel_addr_r}; then tftpboot ${fdt_addr_r} dtb/${efi_fdtfile};if fdt addr ${fdt_addr_r}; then bootefi ${kernel_addr_r} ${fdt_addr_r}; else bootefi ${kernel_addr_r} ${fdtcontroladdr};fi;fi;setenv bootp_vci ${efi_old_vci};setenv bootp_arch ${efi_old_arch};setenv efi_fdtfile;setenv efi_old_arch;setenv efi_old_vci; bootcmd_legacy_mmc0=setenv mmcdev 0; setenv bootpart 0:2 ; run mmcboot bootcmd_legacy_mmc1=setenv mmcdev 1; setenv bootpart 1:2 ; run mmcboot bootcmd_mmc0=setenv devnum 0; run mmc_boot bootcmd_mmc1=setenv devnum 1; run mmc_boot bootcmd_nand=run nandboot bootcmd_pxe=run boot_net_usb_start; dhcp; if pxe get; then pxe boot; fi bootcount=6 bootdelay=2 bootdir=/boot bootenvfile=uEnv.txt bootfile=zImage bootm_size=0x10000000 bootpart=0:2 bootscript=echo Running bootscript from mmc${mmcdev} ...; source ${loadaddr} console=ttyO0115200n8 cpu=armv7 dfu_alt_info_emmc=rawemmc raw 0 3751936;boot part 1 1;rootfs part 1 2;MLO fat 1 1;MLO.raw raw 0x100 0x100;u-boot.img.raw raw 0x300 0x1000;u-env.raw raw 0x1300 0x200;spl-os-args.raw raw 0x1500 0x200;spl-os-image.raw raw 0x1700 0x6900;spl-os-args fat 1 1;spl-os-image fat 1 1;u-boot.img fat 1 1;uEnv.txt fat 1 1 dfu_alt_info_mmc=boot part 0 1;rootfs part 0 2;MLO fat 0 1;MLO.raw raw 0x100 0x100;u-boot.img.raw raw 0x300 0x1000;u-env.raw raw 0x1300 0x200;spl-os-args.raw raw 0x1500 0x200;spl-os-image.raw raw 0x1700 0x6900;spl-os-args fat 0 1;spl-os-image fat 0 1;u-boot.img fat 0 1;uEnv.txt fat 0 1 dfu_alt_info_nand=SPL part 0 1;SPL.backup1 part 0 2;SPL.backup2 part 0 3;SPL.backup3 part 0 4;u-boot part 0 5;u-boot-spl-os part 0 6;kernel part 0 8;rootfs part 0 9 dfu_alt_info_ram=kernel ram 0x80200000 0x4000000;fdt ram 0x80f80000 0x80000;ramdisk ram 0x81000000 0x4000000 distro_bootcmd=for target in ${boot_targets}; do run bootcmd_${target}; done efi_dtb_prefixes=/ /dtb/ /dtb/current/ envboot=mmc dev ${mmcdev}; if mmc rescan; then echo SD/MMC found on device ${mmcdev};if run loadbootscript; then run bootscript;else if run loadbootenv; then echo Loaded env from ${bootenvfile};run importbootenv;fi;if test -n $uenvcmd; then echo Running uenvcmd ...;run uenvcmd;fi;fi;fi; eth1addr=90:70:65:db:2a:7e ethact=ethernet@4a100000 ethaddr=90:70:65:db:2a:7c fdt_addr_r=0x88000000 fdtaddr=0x88000000 fdtcontroladdr=8df1e8f0 fdtfile=undefined findfdt=if test $board_name = A335BONE; then setenv fdtfile am335x-bone.dtb; fi; if test $board_name = A335BNLT; then setenv fdtfile am335x-boneblack.dtb; fi; if test $board_name = A335PBGL; then setenv fdtfile am335x-pocketbeagle.dtb; fi; if test $board_name = BBBW; then setenv fdtfile am335x-boneblack-wireless.dtb; fi; if test $board_name = BBG1; then setenv fdtfile am335x-bonegreen.dtb; fi; if test $board_name = BBGW; then setenv fdtfile am335x-bonegreen-wireless.dtb; fi; if test $board_name = BBBL; then setenv fdtfile am335x-boneblue.dtb; fi; if test $board_name = A33515BB; then setenv fdtfile am335x-evm.dtb; fi; if test $board_name = A335X_SK; then setenv fdtfile am335x-evmsk.dtb; fi; if test $board_name = A335_ICE; then setenv fdtfile am335x-icev2.dtb; fi; if test $fdtfile = undefined; then echo WARNING: Could not determine device tree to use; fi; finduuid=part uuid mmc ${bootpart} uuid fit_bootfile=fitImage fit_loadaddr=0x87000000 importbootenv=echo Importing environment from mmc${mmcdev} ...; env import -t ${loadaddr} ${filesize} init_console=if test $board_name = A335_ICE; then setenv console ttyO3115200n8;else setenv console ttyO0115200n8;fi; ipaddr=172.30.131.12 kernel_addr_r=0x82000000 load_efi_dtb=load ${devtype} ${devnum}{distro_bootpart} ${fdt_addr_r} ${prefix}${efi_fdtfile} loadaddr=0x82000000 loadbootenv=fatload mmc ${mmcdev} ${loadaddr} ${bootenvfile} loadbootscript=load mmc ${mmcdev} ${loadaddr} boot.scr loadfdt=load ${devtype} ${bootpart} ${fdtaddr} ${bootdir}/${fdtfile} loadfit=run args_mmc; bootm ${loadaddr}#${fdtfile}; loadimage=load ${devtype} ${bootpart} ${loadaddr} ${bootdir}/${bootfile} loadramdisk=load mmc ${mmcdev} ${rdaddr} ramdisk.gz mmc_boot=if mmc dev ${devnum}; then setenv devtype mmc; run scan_dev_for_boot_part; fi mmcboot=mmc dev ${mmcdev}; setenv devnum ${mmcdev}; setenv devtype mmc; if mmc rescan; then echo SD/MMC found on device ${mmcdev};if run loadimage; then if test ${boot_fit} -eq 1; then run loadfit; else run mmcloados;fi;fi;fi; mmcdev=0 mmcloados=run args_mmc; if test ${boot_fdt} = yes || test ${boot_fdt} = try; then if run loadfdt; then bootz ${loadaddr} - ${fdtaddr}; else if test ${boot_fdt} = try; then bootz; else echo WARN: Cannot load the DT; fi; fi; else bootz; fi; mmcrootfstype=ext4 rootwait mtdids=nand0=nand.0 mtdparts=mtdparts=nand.0:128k(NAND.SPL)128k(NAND.SPL.backup1)128k(NAND.SPL.backup2)128k(NAND.SPL.backup3)256k(NAND.u-boot-spl-os)1m(NAND.u-boot)128k(NAND.u-boot-env)128k(NAND.u-boot-env.backup1)8m(NAND.kernel)-(NAND.file-system) nandargs=setenv bootargs console=${console} ${optargs} root=${nandroot} rootfstype=${nandrootfstype} nandboot=echo Booting from nand ...; run nandargs; nand read ${fdtaddr} NAND.u-boot-spl-os; nand read ${loadaddr} NAND.kernel; bootz ${loadaddr} - ${fdtaddr} nandroot=ubi0:rootfs rw ubi.mtd=NAND.file-system2048 nandrootfstype=ubifs rootwait=1 netargs=setenv bootargs console=${console} ${optargs} root=/dev/nfs nfsroot=${serverip}{rootpath}${nfsopts} rw ip=dhcp netboot=echo Booting from network ...; setenv autoload no; dhcp; run netloadimage; run netloadfdt; run netargs; bootz ${loadaddr} - ${fdtaddr} netloadfdt=tftp ${fdtaddr} ${fdtfile} netloadimage=tftp ${loadaddr} ${bootfile} nfsopts=nolock partitions=uuid_disk=${uuid_gpt_disk};name=bootloaderstart=384Ksize=1792Kuuid=${uuid_gpt_bootloader};name=rootfsstart=2688Ksize=-uuid=${uuid_gpt_rootfs} pxefile_addr_r=0x80100000 ramargs=setenv bootargs console=${console} ${optargs} root=${ramroot} rootfstype=${ramrootfstype} ramboot=echo Booting from ramdisk ...; run ramargs; bootz ${loadaddr} ${rdaddr} ${fdtaddr} ramdisk_addr_r=0x88080000 ramroot=/dev/ram0 rw ramrootfstype=ext2 rdaddr=0x88080000 rootpath=/export/rootfs scan_dev_for_boot=echo Scanning ${devtype} ${devnum}{distro_bootpart}...; for prefix in ${boot_prefixes}; do run scan_dev_for_extlinux; run scan_dev_for_scripts; done;run scan_dev_for_efi; scan_dev_for_boot_part=part list ${devtype} ${devnum} -bootable devplist; env exists devplist || setenv devplist 1; for distro_bootpart in ${devplist}; do if fstype ${devtype} ${devnum}{distro_bootpart} bootfstype; then run scan_dev_for_boot; fi; done scan_dev_for_efi=setenv efi_fdtfile ${fdtfile}; if test -z "${fdtfile}" -a -n "${soc}"; then setenv efi_fdtfile ${soc}-${board}${boardver}.dtb; fi; for prefix in ${efi_dtb_prefixes}; do if test -e ${devtype} ${devnum}{distro_bootpart} ${prefix}${efi_fdtfile}; then run load_efi_dtb; fi;done;if test -e ${devtype} ${devnum}{distro_bootpart} efi/boot/bootarm.efi; then echo Found EFI removable media binary efi/boot/bootarm.efi; run boot_efi_binary; echo EFI LOAD FAILED: continuing...; fi; setenv efi_fdtfile scan_dev_for_extlinux=if test -e ${devtype} ${devnum}{distro_bootpart} ${prefix}extlinux/extlinux.conf; then echo Found ${prefix}extlinux/extlinux.conf; run boot_extlinux; echo script FAILED: continuing...; fi scan_dev_for_scripts=for script in ${boot_scripts}; do if test -e ${devtype} ${devnum}:${distro_bootpart} ${prefix}${script}; then echo Found U-Boot script ${prefix}${script}; run boot_a_script; echo script FAILED: continuing...; fi; done scriptaddr=0x80000000 serial#=90:70:65:db:2a:7c serverip=172.30.131.200 soc=am33xx spiargs=setenv bootargs console=${console} ${optargs} root=${spiroot} rootfstype=${spirootfstype} spiboot=echo Booting from spi ...; run spiargs; sf probe ${spibusno}:0; sf read ${loadaddr} ${spisrcaddr} ${spiimgsize}; bootz ${loadaddr} spibusno=0 spiimgsize=0x362000 spiroot=/dev/mtdblock4 rw spirootfstype=jffs2 spisrcaddr=0xe0000 static_ip=${ipaddr}:${serverip}:${gatewayip}:${netmask}:${hostname}:ff stderr=serial@44e09000 stdin=serial@44e09000 stdout=serial@44e09000 update_to_fit=setenv loadaddr ${fit_loadaddr}; setenv bootfile ${fit_bootfile} usb_boot=usb start; if usb dev ${devnum}; then setenv devtype usb; run scan_dev_for_boot_part; fi vendor=ti ver=U-Boot 2018.07 (Feb 28 2021 - 18:59:04 -0800) Environment size: 9886/131068 bytes => ping 172.30.131.200 link up on port 0 speed 100 full duplex Using ethernet@4a100000 device ARP Retry count exceeded; starting again ping failed; host 172.30.131.200 is not alive =>
就这个显示一个字符的程序，当中chr是字符串的首地址，也就是要显示字符的地址。第一个问题 然后chr既然是地址。为什么asc2_2412[chr][t]这样用。 这个chr怎么会是一个整数。第二个问题 chr-“ ” 也是很不理解。我知道的是这个asc2_2412[chr][t]数组刚开始是空格的编码。void OLED_ShowChar(u8 xu8 yu8 chru8 sizeu8 mode){ u8 temptt1; u8 y0=y; u8 csize=(size/8+((size%8)?1:0))*(size/2); //μÃμ½×Öìåò»¸ö×Ö·û¶Ôó|μãÕó¼ˉËùÕ¼μÄ×Ö½úêy chr=chr-' ';//μÃμ½Æ«òÆoóμÄÖμ 就是这一句 for(t=0;t<csize;t++) { if(size==12)temp=asc2_1206[chr][t]; //μ÷óÃ1206×Öìå else if(size==16)temp=asc2_1608[chr][t]; //μ÷óÃ1608×Öìå else if(size==24)temp=asc2_2412[chr][t]; //μ÷óÃ2412×Öìå else return; //ûóDμÄ×Ö¿a for(t1=0;t1<8;t1++) { if(temp&0x80)OLED_DrawPoint(xymode); //»-μãoˉêy else OLED_DrawPoint(xy!mode); temp<<=1; y++; if((y-y0)==size) { y=y0; x++; break; } } } }
can't open /dev/ttyAMA0: No such file or directory 全部是这个打印，网络，nfs服务器一切正常，rcS，权限为777， 没有出现无法挂载nfs 失败的情况，网上基本没有这些信息，怎么实验，都不行，在线等
在不带的MMU的MCU上运行嵌入式实时操作系统，如uCos，，可以直接访问寄存器么?在支持MMU的CPU上运行实时操作系统，可以直接访问CPU寄存器么？如能，这时访问的寄存器，需不需奥考虑虚实转换？LInux内核开发过程中可以直接访问CPU的寄存器么
目前因为内部RAM空间不足，想将在内不定义的结构体定义到外部SDRAM中，用__attribute__((at(0xC0300000))); 发现总是会进入到硬件异常中，请教各位大佬有没有什么其它办法？ 如： typedef struct testData { float a[1000]; float b[1000]; float c[1000]; ... }TestData_t; TestData_t testData_t __attribute__((at(0xC0300000))); // 会进入硬件异常
qt警告libpng warning: iCCP: known incorrect sRGB profile
全部分类
