标签: START

几个基本概念： 1、 Genymotion是安卓开发环境的一种模拟器，加载APP的速度比较快（模拟器本身启动也是需要相当长时间）。 2、Genymotion依赖于VirtualBox（著名的开源虚拟机软件，轻巧、好用！），就是说Genymotion跟VirtualBox要一起使用（Genymotion调用了VirtualBox的接口）。 3、Genymotion对VirtualBox的版本理论上没有限制要求（至少Genymotion官方没有说必须使用哪个版本）；但最好使用 Genymotion 提供的VirtualBox版本，比如4.2.12）。 4、Genymotion、VirtualBox的安装顺序不要求谁先谁后，推荐先安装VirtualBox。 5、Genymotion在官方网站上有2个版本可下载：包含VirtualBox的和独立的。如果你的PC上还没有安装VirtualBox，推荐使用前者。如果已安装了VirtualBox，直接用独立版本即可。 6、 Genymotion可作为Eclipse、Android Studio的插件使用，很方便，关键是快，呵呵。   下载、安装的步骤网上很多，不废话了；有2点需要注意： 1、在Genymotion官网上下载时，需要先注册一个用户（免费的），尽量不要用可能被国外屏蔽的mail账号。（139.com也在此之列，呵呵。。。） 2、网上有很多解决 Genymotion安装过程中出现问题的各种“攻略”，但多数没有针对问题的根本原因，比如“换一个VirtualBox版本安装就ok了”、“查找某个log文件里的某个setting字串、按照路径重新安装VirtualBox”等，这些做法也许针对某个人的具体问题有效，但没有普遍性，没有触及问题实质。 言归正传，如果启动 Genymotion中的某个虚拟设备（手机）：     （在上图中点击 Start 启动一个模拟手机） 结果出现：   unable to start the virtual device. 这表明 Genymotion在正常运行，但创建模拟手机失败；此时，先退出 Genymotion，启动VirtualBox来运行模拟手机（VirtualBox的使用不在这里说了，不熟悉的同学baidu一下），应该能正常出现手机画面（经历一个漫长的时间过程，呵呵）。如果这个过程异常，那就首先是VirtualBox的问题了，怎么解决找baidu吧。 VirtualBox能正常启动模拟手机画面的前提下，关闭手机画面，检查 VirtualBox的配置（虚拟设备的网络配置）：     步骤： 1、选择 虚拟设备 2、点选 设置 3、点选 网络 4、网卡1 应该 “启用网络连接”，连接方式是 host-only，关键是下面界面名称里，必须是 virtualBox Host-Only Ethernet Adapter （这是一个虚拟网卡，VirtualBox自动安装的）。如果 界面名称 里是空的、未安装、未选择之类，就会出现上面 Genymotion的 unable to start the virtual device.  问题！！   本人使用的WIN7，网络连接中的 本地连接 不知何种原因“消失”了，导致   virtualBox Host-Only Ethernet Adapter 这个驱动异常，从而导致 unable to start the virtual device！（ 问题的本质是：VirtualBox网络配置不正确，导致Genymotion不能跟VirtualBox正常通讯，也就不能通过VirtualBox正常创建虚拟设备 ） WIN7的 本地连接 消失是个普遍问题，可baidu解决方法。找回 本地连接后，再启动 Genymotion，创建模拟手机就正常了！   至于说是否需要设置上面的 Host-Only适配器的IP地址，这是不需要的，VirtualBox很智能，安装时自动配置了DHCP，IP自动可获得。   BTW，细心的用户可能发现VirtualBox的网卡配置,，还有个 网卡2，并且配置成了NAT（网络地址转换），这个的作用是：使得模拟手机中的APP（比如：浏览器）可以访问internet。 以上是本人周末折腾了2天Genymotion和VirtualBox的小结，希望对大家有用；不对的地方欢迎拍砖。   参考： 1、VirtualBox的四种网络接入模式 http://wenku.baidu.com/view/14e69aefaeaad1f346933f32.html http://blog.csdn.net/yxc135/article/details/8458939 2、 Genymotion的安装过程 http://www.iplaysoft.com/genymotion.html 3、 Genymotion的官方使用文档 https://www.genymotion.com/#!/developers/user-guide  

Being a company's CEO can be a lonely position. This is especially true among startups. For this reason, I strongly advocate having a mentor. Finding the right mentor, however, may be more important than having one. In this blog I talk about how to recruit a mentor, what qualities to look for, and touch briefly on the compensation.       Finding the right mentor should not be a random choice or one done without some consideration. The mentor you choose should have an understanding of your business and why decisions are being made the way they are. Preferably, the chosen mentor has been an entrepreneur and CEO as well. That's not to suggest a mentor should be involved in day-to-day decision making, however. Someone with experience, who maintains a safe distance from the daily business activities, can offer much-needed perspective.   First, a mentor needs to be a good listener: A good mentor will guide an entrepreneur through the process and empower him or her to come up with the right answer, not give answers. Indeed, the entrepreneur has the great advantage of knowing the business better than anyone else. The role of the mentor is to help the entrepreneur sift through many options or give him or her a boost of confidence to implement a new program.   That's why building a great mentor relationship includes open lines of communication. It is a dialog where each of you approaches the other by asking questions on why and how decisions are made. The discussion will flow from there.   Think of it as establishing a peer-to-peer relationship because you will be working at a personal level. The mentor will serve as a sounding board and can help through the emotional ups and downs. And, there will be many.   Obviously, you're wondering how to go about finding the right person. The answer is there's a maze of different possibilities. A good place to start is to consider which entrepreneurs or corporate executives you admire and want to emulate. That's not to say they will accept your proffered invitation. Or, that they're a good fit once you get to know them. It's well worth making the effort because they may refer you to someone who is a better fit.   Your own network should be tapped, too, to identify potential mentor candidates with relevant experience. Having first-hand, working knowledge of an industry is what to look for. Ask around to find out his or her reputation to better assess strengths or perceived weaknesses.   It’s also not unusual for one of the members of the board of directors to take a more active role as mentor to the new CEO. A potential benefit of this approach, though, is that the mentor becomes an ally at the board level since the mentor would have reviewed and presumably approved key decisions. Of course, the board member/mentor will make sure that he or she still exercises the fiduciary duties of a board member, regardless of the more personal relationship built with the CEO.   Angel investors are good candidates to become mentors. They like to relive the glory days vicariously through investments and the entrepreneurs driving the companies. They’re interested also in helping you succeed.   Mentors can help with a specific need over a limited period of time. For example, if the start-up founding team is weak on the sales side, a seasoned vice president of sales can help build a channel. Or a marketing executive can counsel you on plotting the timeline for your go-to-market strategy. Other experienced executives could come from a customer or a supplier. You might consider approaching a university professor to assist in the technical vision of the company.   As for compensation, entrepreneurs typically offer stock options rather than cash when the company is still in the startup phase. Stock has another advantage as well because it could give a mentor an added attachment to the company and an even stronger desire to see it succeed. An appropriate equity stake for a mentor would be in the 0.25% to 1.0% range, with the higher number more appropriate for an early stage company.   In this blog, I focused on the entrepreneur’s view of having a mentor, but I’ll close with why someone would want to be a mentor. Among the many benefits, it’s profoundly satisfying to help an entrepreneurial company triumph knowing you’ve played a role.   Michel Courtoy is a former design engineer and EDA executive who sits on the board of directors at Breker Verification Systems.

The CEO spot in a company, especially a startup, can be a lonely one. For this reason, I strongly advocate having a mentor. Finding the right mentor, however, may be more important than having one. In this blog I talk about how to recruit a mentor, what qualities to look for, and touch briefly on the compensation.       Finding the right mentor should not be a random choice or one done without some consideration. The mentor you choose should have an understanding of your business and why decisions are being made the way they are. Preferably, the chosen mentor has been an entrepreneur and CEO as well. That's not to suggest a mentor should be involved in day-to-day decision making, however. Someone with experience, who maintains a safe distance from the daily business activities, can offer much-needed perspective.   First, a mentor needs to be a good listener: A good mentor will guide an entrepreneur through the process and empower him or her to come up with the right answer, not give answers. Indeed, the entrepreneur has the great advantage of knowing the business better than anyone else. The role of the mentor is to help the entrepreneur sift through many options or give him or her a boost of confidence to implement a new program.   That's why building a great mentor relationship includes open lines of communication. It is a dialog where each of you approaches the other by asking questions on why and how decisions are made. The discussion will flow from there.   Think of it as establishing a peer-to-peer relationship because you will be working at a personal level. The mentor will serve as a sounding board and can help through the emotional ups and downs. And, there will be many.   Obviously, you're wondering how to go about finding the right person. The answer is there's a maze of different possibilities. A good place to start is to consider which entrepreneurs or corporate executives you admire and want to emulate. That's not to say they will accept your proffered invitation. Or, that they're a good fit once you get to know them. It's well worth making the effort because they may refer you to someone who is a better fit.   Your own network should be tapped, too, to identify potential mentor candidates with relevant experience. Having first-hand, working knowledge of an industry is what to look for. Ask around to find out his or her reputation to better assess strengths or perceived weaknesses.   It’s also not unusual for one of the members of the board of directors to take a more active role as mentor to the new CEO. A potential benefit of this approach, though, is that the mentor becomes an ally at the board level since the mentor would have reviewed and presumably approved key decisions. Of course, the board member/mentor will make sure that he or she still exercises the fiduciary duties of a board member, regardless of the more personal relationship built with the CEO.   Angel investors are good candidates to become mentors. They like to relive the glory days vicariously through investments and the entrepreneurs driving the companies. They’re interested also in helping you succeed.   Mentors can help with a specific need over a limited period of time. For example, if the start-up founding team is weak on the sales side, a seasoned vice president of sales can help build a channel. Or a marketing executive can counsel you on plotting the timeline for your go-to-market strategy. Other experienced executives could come from a customer or a supplier. You might consider approaching a university professor to assist in the technical vision of the company.   As for compensation, entrepreneurs typically offer stock options rather than cash when the company is still in the startup phase. Stock has another advantage as well because it could give a mentor an added attachment to the company and an even stronger desire to see it succeed. An appropriate equity stake for a mentor would be in the 0.25% to 1.0% range, with the higher number more appropriate for an early stage company.   In this blog, I focused on the entrepreneur’s view of having a mentor, but I’ll close with why someone would want to be a mentor. Among the many benefits, it’s profoundly satisfying to help an entrepreneurial company triumph knowing you’ve played a role.   Michel Courtoy is a former design engineer and EDA executive who sits on the board of directors at Breker Verification Systems.

/*写在这就是为了给自己做个笔记 如果有理解不正确的地方 还望指正*/ #include #include /*  *************************************************************************  *  * Jump vector table as in table 3.1 in  *  *************************************************************************  */ //构建异常向量表 .globl _start _start:    b       reset     ldr    pc, _undefined_instruction//未定义指令     ldr    pc, _software_interrupt//软中断     ldr    pc, _prefetch_abort     ldr    pc, _data_abort     ldr    pc, _not_used     ldr    pc, _irq//中断 可被快速中断中断     ldr    pc, _fiq//快速中断 _undefined_instruction:    .word undefined_instruction _software_interrupt:    .word software_interrupt _prefetch_abort:    .word prefetch_abort _data_abort:        .word data_abort _not_used:        .word not_used _irq:            .word irq _fiq:            .word fiq //ldr pc ， a  把a这个地址的值读到pc中 //ldr pc ，=a  把a这个地址读到pc中 //上面两段这种写法相当于c语言的指针。     .balignl 16,0xdeadbeef /*  *************************************************************************  *  * Startup Code (reset vector)  *  * do important init only if we don't start from memory!  * relocate armboot to ram  * setup stack  * jump to second stage  *  *************************************************************************  */ _TEXT_BASE:     .word    TEXT_BASE//在board/smdk2410/config.mk里面有定义 为0x33f80000 是代码在sdram里面的首地址，所有也是 编译的基地址。 .globl _armboot_start _armboot_start:     .word _start /*     和上面的一样 armboot_start 相当于一个变量，里面放的是start 就是代码的首地址， */ /*  * These are defined in the board-specific linker script.  */ .globl _bss_start _bss_start:     .word __bss_start .globl _bss_end _bss_end:     .word _end #ifdef CONFIG_USE_IRQ /* IRQ stack memory (calculated at run-time) */ .globl IRQ_STACK_START IRQ_STACK_START:     .word    0x0badc0de /* IRQ stack memory (calculated at run-time) */ .globl FIQ_STACK_START FIQ_STACK_START:     .word 0x0badc0de #endif /*  * the actual reset code  */ reset:     /*      * set the cpu to SVC32 mode      */     mrs    r0,cpsr     bic    r0,r0,#0x1f     orr    r0,r0,#0xd3     msr    cpsr,r0 /* turn off the watchdog */ #if defined(CONFIG_S3C2400) # define pWTCON        0x15300000 # define INTMSK        0x14400008    /* Interupt-Controller base addresses */ # define CLKDIVN    0x14800014    /* clock divisor register */ #elif defined(CONFIG_S3C2410) # define pWTCON        0x53000000 # define INTMSK        0x4A000008    /* Interupt-Controller base addresses */ # define INTSUBMSK    0x4A00001C # define CLKDIVN    0x4C000014    /* clock divisor register */ #endif //具体实现关看门狗 因为在程序刚开始 定时器什么都没有初始化 不关看门狗 系统就会不停复位 #if defined(CONFIG_S3C2400) || defined(CONFIG_S3C2410)     ldr     r0, =pWTCON     mov     r1, #0x0     str     r1, //把r1寄存器的值写入r0寄存器指向的地址中去     /*      * mask all IRQs by setting all bits in the INTMR - default      下面关闭所有屏蔽所有中断      */     mov    r1, #0xffffffff     ldr    r0, =INTMSK     str    r1, # if defined(CONFIG_S3C2410)     ldr    r1, =0x3ff     ldr    r0, =INTSUBMSK     str    r1, # endif     /* FCLK:HCLK:PCLK = 1:2:4 */     /* default FCLK is 120 MHz ! 初始化时钟*/     ldr    r0, =CLKDIVN     mov    r1, #3     str    r1, #endif    /* CONFIG_S3C2400 || CONFIG_S3C2410 */     /*      * we do sys-critical inits only at reboot,      * not when booting from ram!      */ #ifndef CONFIG_SKIP_LOWLEVEL_INIT     bl    cpu_init_crit//这个函数在下面     //bl 是带返回的跳转，跳转之前会把当前pc地址给r14 ，执行完之后会返回 b是不带返回的跳转 但两个都是基于pc的跳转，这样就实现地址无关的写法 #endif #ifndef CONFIG_SKIP_RELOCATE_UBOOT relocate:                /* relocate U-Boot to RAM        */     adr    r0, _start        /* r0 - current position of code   */     ldr    r1, _TEXT_BASE        /* test if we run from flash or RAM */     cmp     r0, r1                  /* don't reloc during debug         */     beq     stack_setup//如果两个值一样 说明已经在sdram里面执行程序了 就不用拷贝了 不一样就拷贝到sdram中去 就是下面代码     ldr    r2, _armboot_start     ldr    r3, _bss_start     sub    r2, r3, r2        /* r2 - size of armboot            */     add    r2, r0, r2        /* r2 - source end address         */ copy_loop:     ldmia    r0!, {r3-r10}        /* copy from source address     */     stmia    r1!, {r3-r10}        /* copy to   target address     */     cmp    r0, r2            /* until source end addreee     */     ble    copy_loop #endif    /* CONFIG_SKIP_RELOCATE_UBOOT */     /* Set up the stack        下面是设置栈 可以参照p260的图(韦东山老师的书) 就是在基地址上减去各种预留空间                    */ stack_setup:     ldr    r0, _TEXT_BASE        /* upper 128 KiB: relocated uboot   */     sub    r0, r0, #CFG_MALLOC_LEN    /* malloc area                      */     sub    r0, r0, #CFG_GBL_DATA_SIZE /* bdinfo                        */ #ifdef CONFIG_USE_IRQ     sub    r0, r0, #(CONFIG_STACKSIZE_IRQ+CONFIG_STACKSIZE_FIQ) #endif     sub    sp, r0, #12        /* leave 3 words for abort-stack    */ /*下面代码是清bss BSS（Block Started by Symbol）通常是指用来存放程序中未初始化的全局变量和静态变量的一块内存区域。 特点是:可读写的，在程序执行之前BSS段会自动清0。BSS存放的是未初始化的全局变量和静态变量， 数据段存放的是初始化后的全局变量和静态变量。 */ clear_bss:     ldr    r0, _bss_start        /* find start of bss segment        */     ldr    r1, _bss_end        /* stop here                        */     mov     r2, #0x00000000        /* clear                            */ clbss_l:str    r2,         /* clear loop...                    */     add    r0, r0, #4     cmp    r0, r1     ble    clbss_l //if 0  这段代码不会执行 但为什么要写在这？？？ 而且是前面已经执行过的代码 #if 0     /* try doing this stuff after the relocation */     ldr     r0, =pWTCON     mov     r1, #0x0     str     r1,     /*      * mask all IRQs by setting all bits in the INTMR - default      */     mov    r1, #0xffffffff     ldr    r0, =INTMR     str    r1,     /* FCLK:HCLK:PCLK = 1:2:4 */     /* default FCLK is 120 MHz ! */     ldr    r0, =CLKDIVN     mov    r1, #3     str    r1,     /* END stuff after relocation */ #endif     ldr    pc, _start_armboot//进入第二阶段 _start_armboot:    .word start_armboot /*  *************************************************************************  *  * CPU_init_critical registers  *  * setup important registers  * setup memory timing  *  *************************************************************************  */ #ifndef CONFIG_SKIP_LOWLEVEL_INIT cpu_init_crit:     /*      * flush v4 I/D caches      因为刚开始 caches里面的数据不是我们指定的数据 不能使用 所以要flush      */     mov    r0, #0     mcr    p15, 0, r0, c7, c7, 0    /* flush v3/v4 cache */     mcr    p15, 0, r0, c8, c7, 0    /* flush v4 TLB */ // //p15是arm协处理器 mcr：把r0的数据读出来给c8 第一个0是固定为0，接下来是arm寄存器，协处理器寄存器， //p15协处理器寄存器有时候一个寄存器有多种用途 这就要根据最后面一位来决定 不用为0 //mrc和mcr刚好相反     /*      * disable MMU stuff and caches      */     mrc    p15, 0, r0, c1, c0, 0     bic    r0, r0, #0x00002300    @ clear bits 13, 9:8 (--V- --RS)     bic    r0, r0, #0x00000087    @ clear bits 7, 2:0 (B--- -CAM)     orr    r0, r0, #0x00000002    @ set bit 2 (A) Align     orr    r0, r0, #0x00001000    @ set bit 12 (I) I-Cache     mcr    p15, 0, r0, c1, c0, 0     /*      * before relocating, we have to setup RAM timing      * because memory timing is board-dependend, you will      * find a lowlevel_init.S in your board directory.      */     mov    ip, lr//lr就是r14，此时r14保存跳转的地址，把这个地址给r12，以便返回。ip（R12） SP（R13） LR（R14）PC（R15）     bl    lowlevel_init//这个文件在board/smdk2410/lowlevel_init.s 是对sdram进行初始化     mov    lr, ip     mov    pc, lr//取出地址，返回。 #endif /* CONFIG_SKIP_LOWLEVEL_INIT */ /*  *************************************************************************  *  * Interrupt handling  *  *************************************************************************  */ @ @ IRQ stack frame. @ #define S_FRAME_SIZE    72 #define S_OLD_R0    68 #define S_PSR        64 #define S_PC        60 #define S_LR        56 #define S_SP        52 #define S_IP        48 #define S_FP        44 #define S_R10        40 #define S_R9        36 #define S_R8        32 #define S_R7        28 #define S_R6        24 #define S_R5        20 #define S_R4        16 #define S_R3        12 #define S_R2        8 #define S_R1        4 #define S_R0        0 #define MODE_SVC 0x13 #define I_BIT     0x80 /*  * use bad_save_user_regs for abort/prefetch/undef/swi ...  * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling  下面所有的都是异常处理函数 不过bad_save_user_regs  irq_save_user_regs  分别用这两个来处理异常和中断。  */     .macro    bad_save_user_regs     sub    sp, sp, #S_FRAME_SIZE     stmia    sp, {r0 - r12}            @ Calling r0-r12     ldr    r2, _armboot_start     sub    r2, r2, #(CONFIG_STACKSIZE+CFG_MALLOC_LEN)     sub    r2, r2, #(CFG_GBL_DATA_SIZE+8)  @ set base 2 words into abort stack     ldmia    r2, {r2 - r3}            @ get pc, cpsr     add    r0, sp, #S_FRAME_SIZE        @ restore sp_SVC     add    r5, sp, #S_SP     mov    r1, lr     stmia    r5, {r0 - r3}            @ save sp_SVC, lr_SVC, pc, cpsr     mov    r0, sp     .endm     .macro    irq_save_user_regs     sub    sp, sp, #S_FRAME_SIZE     stmia    sp, {r0 - r12}            @ Calling r0-r12     add     r8, sp, #S_PC     stmdb   r8, {sp, lr}^                   @ Calling SP, LR     str     lr,                     @ Save calling PC     mrs     r6, spsr     str     r6,                     @ Save CPSR     str     r0,                     @ Save OLD_R0     mov    r0, sp     .endm     .macro    irq_restore_user_regs     ldmia    sp, {r0 - lr}^            @ Calling r0 - lr     mov    r0, r0     ldr    lr,             @ Get PC     add    sp, sp, #S_FRAME_SIZE     subs    pc, lr, #4            @ return move spsr_svc into cpsr     .endm     .macro get_bad_stack     ldr    r13, _armboot_start        @ setup our mode stack     sub    r13, r13, #(CONFIG_STACKSIZE+CFG_MALLOC_LEN)     sub    r13, r13, #(CFG_GBL_DATA_SIZE+8) @ reserved a couple spots in abort stack     str    lr,             @ save caller lr / spsr     mrs    lr, spsr     str     lr,     mov    r13, #MODE_SVC            @ prepare SVC-Mode     @ msr    spsr_c, r13     msr    spsr, r13     mov    lr, pc     movs    pc, lr     .endm     .macro get_irq_stack            @ setup IRQ stack     ldr    sp, IRQ_STACK_START     .endm     .macro get_fiq_stack            @ setup FIQ stack     ldr    sp, FIQ_STACK_START     .endm /*  * exception handlers    */     .align  5 undefined_instruction:     get_bad_stack     bad_save_user_regs     bl     do_undefined_instruction     .align    5 software_interrupt:     get_bad_stack     bad_save_user_regs     bl     do_software_interrupt     .align    5 prefetch_abort:     get_bad_stack     bad_save_user_regs     bl     do_prefetch_abort     .align    5 data_abort:     get_bad_stack     bad_save_user_regs     bl     do_data_abort     .align    5 not_used:     get_bad_stack     bad_save_user_regs     bl     do_not_used #ifdef CONFIG_USE_IRQ     .align    5 irq:     get_irq_stack     irq_save_user_regs     bl     do_irq     irq_restore_user_regs     .align    5 fiq:     get_fiq_stack     /* someone ought to write a more effiction fiq_save_user_regs */     irq_save_user_regs     bl     do_fiq     irq_restore_user_regs #else     .align    5 irq:     get_bad_stack     bad_save_user_regs     bl     do_irq     .align    5 fiq:     get_bad_stack     bad_save_user_regs     bl     do_fiq #endif