TQE9开发板QNX系统下载graphic镜像

问题描述：TQE9开发板下载带有图形界面的qnx-ifs系统镜像后总是无法启动，卡在Load QNX image from SDMMC...

分析问题之前，先分析一下sabreARD-graphics.build的启动脚本，镜像文件说明如下：

[image=0x10800000]# For u-boot, IFS image should be uncompressed[virtual=armle-v7,raw] .bootstrap = {# For IPL, IFS image should be compressed#[virtual=armle-v7,raw +compress] .bootstrap = {    # Startup parameters:    # '-b' -> enable BT (conflicts with SPI NOR and PCIe)    # '-m' -> enable d-cache/MMU (improves boot time)    # '-W' -> enable watchdog (wdtkick should be uncommented when using this option)    # Note:only ONE of below option may be selected for NOR flash    # '-n0' -> no NOR Flash (I2C3 enabled)    # '-n1' -> parallel NOR Flash (I2C3 disabled)    # '-n2' -> SPI NOR Flash (I2C3 disabled)    #    # '-c' -> CAN startup option (conflicts with Ethernet)    # '-s' -> Use SDMA to load IFS    # '-r' -> to reserve the top 256M of RAM (0x80000000 -- 0x8FFFFFFF) so that    # screen will work properly. There is an issue with the graphics processor    # on the i.MX6 Quad Plus  where the code will not run if allocated in this    # block of memory. This is an interm fix until the problem is resolved by    # NXP.    # startup-imx6x-sabreARD -n0 -m -r 0x80000000,256M    # Otherwise use the following version of startup to access the full range of RAM    startup-imx6x-sabreARD -n1 -m -W -s    PATH=/proc/boot:/bin:/usr/bin:/opt/bin/sbin:/usr/sbin LD_LIBRARY_PATH=/proc/boot:/lib:/usr/lib:/lib/dll:/lib/dll/pci:/opt/lib procnto-smp-instr}

image表示镜像需要加载到的地址，也就是系统会从该地址启动。查看手册virtual属性的配置格式为：virtual=[cpu_name ,]bootfile_name [filter_args ]。

armle-v7：CPU type

raw：Create a binary image with an instruction sequence at its beginning to jump
that when you download a raw image to memory using a bootloader, you can
then instruct it to run right at the beginning of the image, rather than having
to figure out what the actual startup_vaddr is each time you modify the
startup code.

+compress: compress flag.

compress参数会指明要不要对镜像进行压缩。对于u-boot来讲，镜像是不可以被压缩的，否则设备无法启动。默认加载的镜像image地址是0x10800000，如果代码中加载镜像的地址与build中image值不一致，则需要使用-s参数，使用SDMA加载IFS。

分析我单板的问题：无论是否进行压缩，单板始终都无法正常启动，但同样生成的不带graphic的镜像却可以正常启动，经过层层定位分析：问题出现在接口fat_copy_file上，该接口的逻辑实现:如果当前存储数据的块是连续的，则会一次性把连续块上的内容全部读取出来；如果不连续，则只读当前块的内容。问题就是一次性把连续块上的内容都读取出来的时候存在异常，这个也不知道是emmc的问题还是bsp版本实现的问题。当我们强制让emmc分多次将连续块上的内容分多次读取出来的时候，大包便可以启动了。代码如下：

/*  copy a file from to a memory location */static intfat_copy_file(unsigned cluster, unsigned size, unsigned char *buf){  #if 1    int        result, txf;    unsigned   prev_c, next_c, curr_c;    int     sz  = (int)size;    int     cbytes = fs_info.cluster_size*SECTOR_SIZE;    int actual_len = 0;    if(sdmmc_debug > 1)    { ser_putstr((char *)"fat_copy_file: cs 0x"); ser_puthex(fs_info.cluster_size); ser_putstr((char *)" size 0x"); ser_puthex(sz); ser_putstr((char *)"type 0x"); ser_puthex(fs_info.fat_type ); ser_putstr((char *)"\n");    }#if 1cache_valid = 1;#endifg_fat_sector = -1;    /*    *Note that this impl assume the following:    * 1) The max DMA transfer size is bigger than the max consolidate transfer size    * Otherwise, we need to break down into smaller transfer.    * 2) we always do at least one whole cluster transfer. This might overwrite the client buffer, but    * since this is purely used for IPL, we don't care about that now.    */    curr_c = cluster;    while(sz>0){        txf = cbytes;        prev_c = curr_c;        while(sz>txf){           //try consolidate contigus entry;            next_c = fat_get_fat_entry(curr_c);            if(next_c == (curr_c+1)  && txf > 20*SECTOR_SIZE){                txf +=cbytes;                curr_c = next_c;            }else{                curr_c = next_c;                break;            }        }        if(sdmmc_debug > 4)        {ser_putstr((char *)"blkcnt 0x");ser_puthex(txf/SECTOR_SIZE);ser_putstr((char *)" p 0x");ser_puthex(prev_c);ser_putstr((char *)" n 0x");ser_puthex(curr_c);ser_putstr((char *)"\n");        }        //read the contig cluster out        result= read_fsector(cluster2fsector(prev_c), buf, txf/SECTOR_SIZE) ;        if (result != SDMMC_OK)           return result;        sz     -= txf;        buf  += txf;        actual_len += txf;    }#else  int     sz  = (int)size;    while(!end_of_file(cluster) && (sz > 0)) {        int txf = MIN(sz, fs_info.cluster_size * SECTOR_SIZE);        if (SDMMC_OK != read_cluster(cluster, buf, txf)) {        ser_putstr("      Error - read_clust(): clust buf txf = ");        ser_puthex((unsigned int)clust); ser_putstr(" ");        ser_puthex((unsigned int)buf); ser_putstr(" ");        ser_puthex((unsigned int)txf); ser_putstr("\n");            return SDMMC_ERROR;        }        ser_putstr((char *)"cluster %x");        ser_puthex(cluster);        ser_putstr((char *)"\n");        sz   -= txf;        buf  += txf;        cluster = fat_get_fat_entry(cluster);    }#endif    if(sdmmc_debug > 0)    {    ser_putstr("Actual read fs size = 0x");    ser_puthex(actual_len);    ser_putstr("\n");    }    return SDMMC_OK;}

上述代码的修改地方是将if(next_c == (curr_c+1))改为if(next_c == (curr_c+1) && txf >20*SECTOR_SIZE)，即将连续块上超过10M的数据的分多次读写。这样修改完成之后，镜像可以正常启动。

经过试验后得出以下两条结论：
1、压缩情况下,只要地址不同（build文件中的image值和ipl文件main函数中的QNX_LOAD_ADDR值不同），启动参数无论是否包含-s，镜像均可以正常启动。（由于需要解压缩，所以大包加载的地址必须不能和build中的image地址不同，否则无法解压缩）
2、不压缩情况下，地址若相同，无论是否加-s，都可以正常启动；但若地址不同，只有不加-s的时候才可以正常启动。