龙芯2k1000-pmon（5）- pmon无法修改环境变量的问题

这是在用的时候想修改原有环境变量，但是莫名的出了问题，这篇来追查这个问题的原因。

1. 错误的样式

新增（原来不存在的变量）似乎是没有问题，但是修改原有环境变量的值，就变成了全ff

上图中是用al1举例说明的。

修改之后，重启，环境变量就不可用了。

1.1 还有一个新发现：先删除后加入，就不会有问题

修改后重启，环境变量确实是更新了。

2. 源代码保留一份吧，方便以后查找问题

int tgt_setenv(char *name, char *value)
{char *ep;int envlen;char *nvrambuf;char *nvramsecbuf;
#ifdef NVRAM_IN_FLASHchar *nvram;
#endif/* Non permanent vars. */if (strcmp(EXPERT, name) == 0) {return (1);}/* Calculate total env mem size requiered */envlen = strlen(name);   //变量名的长度if (envlen == 0) {return (0);}if (value != NULL) {envlen += strlen(value);  //加上对应值的长度}envlen += 2;       /* '=' + null byte */  //多用两个字节if (envlen > 255) {                  //超出范围return (0);    /* Are you crazy!? */}/* Use first defined flash device (we probably have only one) */
#ifdef NVRAM_IN_FLASHnvram = (char *)(tgt_flashmap())->fl_map_base;    //0xbfc00000/* Deal with an entire sector even if we only use part of it */nvram += NVRAM_OFFS & ~(NVRAM_SECSIZE - 1);   //0xbfcff000
#endif/* If NVRAM is found to be uninitialized, reinit it. */if (nvram_invalid) {  //0 表示已经初始化了printf("2022-03-08 tgt_setenv nvram_invalid\n");nvramsecbuf = (char *)malloc(NVRAM_SECSIZE);if (nvramsecbuf == 0) {printf("Warning! Unable to malloc nvrambuffer!\n");return (-1);}
#ifdef NVRAM_IN_FLASHmemcpy(nvramsecbuf, nvram, NVRAM_SECSIZE);
#endifnvrambuf = nvramsecbuf + (NVRAM_OFFS & (NVRAM_SECSIZE - 1));memset(nvrambuf, -1, NVRAM_SIZE);nvrambuf[2] = '\0';nvrambuf[3] = '\0';cksum((void *)nvrambuf, NVRAM_SIZE, 1);printf("Warning! NVRAM checksum fail. Reset!\n");
#ifdef NVRAM_IN_FLASH#ifdef BOOT_FROM_NANDmemcpy(nvram, nvramsecbuf, NVRAM_SECSIZE);//update_env_to_nand( nvram, nvramsecbuf,NVRAM_SECSIZE);update_rom_to_nand_1block(nvram,(char *)(tgt_flashmap())->fl_map_base);
#elseif (fl_erase_device(nvram, NVRAM_SECSIZE, FALSE)) {printf("Error! Nvram erase failed!\n");free(nvramsecbuf);return (-1);}if (fl_program_device(nvram, nvramsecbuf, NVRAM_SECSIZE, FALSE)) {printf("Error! Nvram init failed!\n");free(nvramsecbuf);return (-1);}
#endif#elsenvram_put(nvramsecbuf);
#endifnvram_invalid = 0;free(nvramsecbuf);}//end if (nvram_invalid)/* Remove any current setting */tgt_unsetenv(name);    //删除原来的/* Find end of evironment strings */nvramsecbuf = (char *)malloc(NVRAM_SECSIZE);   //分配一片空间 500字节if (nvramsecbuf == 0) {printf("Warning! Unable to malloc nvrambuffer!\n");return (-1);}
#ifndef NVRAM_IN_FLASHnvram_get(nvramsecbuf);
#elsememcpy(nvramsecbuf, nvram, NVRAM_SECSIZE); //把数据都回来
#endifnvrambuf = nvramsecbuf + (NVRAM_OFFS & (NVRAM_SECSIZE - 1));//printf("2022-03-08 nvrambuf = %p nvramsecbuf = %p\n",nvrambuf,nvramsecbuf);/* Etheraddr is special case to save space */
#if 1               /*added by tangyt */if (strcmp("activecom", name) == 0) {activecom = strtoul(value, 0, 0);printf("set activecom to com %d\n", activecom);} else if (strcmp("em_enable", name) == 0) {em_enable = strtoul(value, 0, 0);printf("set em_enable to com %d\n", em_enable);} else
#endifif (strcmp("ethaddr", name) == 0) {   //如果名字是"ethaddr"char *s = value;int i;int32_t v;for (i = 0; i < 6; i++) {gethex(&v, s, 2);hwethadr[i] = v;s += 3;   /* Don't get to fancy here :-) */}}else {  //不是"ethaddr"ep = nvrambuf + 2;if (*ep != '\0') {do {while (*ep++ != '\0') ;} while (*ep++ != '\0');ep--;}if (((int)ep + NVRAM_SIZE - (int)ep) < (envlen + 1)) {free(nvramsecbuf);return (0); /* Bummer! */}/**  Special case heaptop must always be first since it*  can change how memory allocation works.*/if (strcmp("heaptop", name) == 0) {bcopy(nvrambuf + 2, nvrambuf + 2 + envlen,ep - nvrambuf + 1);ep = nvrambuf + 2;while (*name != '\0') {*ep++ = *name++;}if (value != NULL) {*ep++ = '=';while ((*ep++ = *value++) != '\0') ;} else {*ep++ = '\0';}} else {while (*name != '\0') {*ep++ = *name++;}if (value != NULL) {*ep++ = '=';while ((*ep++ = *value++) != '\0') ;} else {*ep++ = '\0';}*ep++ = '\0'; /* End of env strings */}}cksum(nvrambuf, NVRAM_SIZE, 1);
#ifdef NVRAM_IN_FLASHbcopy(&activecom, &nvrambuf[ACTIVECOM_OFFS], 1);bcopy(&em_enable, &nvrambuf[MASTER_BRIDGE_OFFS], 1);
#endifbcopy(hwethadr, &nvramsecbuf[ETHER_OFFS], 6);
#ifdef NVRAM_IN_FLASH#ifdef BOOT_FROM_NANDmemcpy(nvram, nvramsecbuf, NVRAM_SECSIZE);//update_env_to_nand( nvram, nvramsecbuf,NVRAM_SECSIZE);update_rom_to_nand_1block(nvram, (char *)(tgt_flashmap())->fl_map_base);
#elseif (fl_erase_device(nvram, NVRAM_SECSIZE, FALSE)) {printf("Error! Nvram erase failed!\n");free(nvramsecbuf);return (0);}if (fl_program_device(nvram, nvramsecbuf, NVRAM_SECSIZE, FALSE)) {printf("Error! Nvram program failed!\n");free(nvramsecbuf);return (0);}
#endif#else  // ifdef NVRAM_IN_FLASH 不执行nvram_put(nvramsecbuf);
#endiffree(nvramsecbuf);return (1);
}

3. 结合上述的现象，修改失败原因不明。所以想修改一下流程：就是要删除的变量，不再从flash中删除（先读出来，再写进去），而是想直接在内存中改，然后再写进入flash。

3.1 在调试的时候，还发现一旦调用了删除环境变量的操作后，再次读取flash的数据就变为了0xff。不知道是设备忙，还是没写进去，还是什么原因。

3.2 修改后的代码（原环境变量读到内存中，直接在内存中修改，再写入flash一次），功能可用了。感觉可能的原因是不能短时间内多次编程/擦擦操作flash

//2022-03-08 added by zhaozhi
//在内存中把某个环境变量删除
//返回1，表示成功，0表示越界，不要写入flash
static int tgt_setenv_inmem(const char* name,const char* value,int envlen,char * nvrambuf)
{char *ep = nvrambuf + 2;char *np,*sp;while ((*ep != '\0') && (ep <= nvrambuf + NVRAM_SIZE)) {np = name;sp = ep;while ((*ep == *np) && (*ep != '=') && (*np != '\0')) {  //找到了相同的名字ep++;np++;}if ((*np == '\0') && ((*ep == '\0') || (*ep == '='))) {while (*ep++) ;while (ep <= nvrambuf + NVRAM_SIZE) {*sp++ = *ep++;   //把后面的数据移过来}if (nvrambuf[2] == '\0') {   //全部删除完了，没得数据了nvrambuf[3] = '\0';    //连续两个0}//  cksum(nvrambuf, NVRAM_SIZE, 1);  //算出校验和，填充      break;} else if (*ep != '\0') {   //不等于0，就表示前面没找到相同的while (*ep++ != '\0') ;}}//把数据加进去{  //不是"ethaddr"ep = nvrambuf + 2;if (*ep != '\0') {    //指针向后移动do {while (*ep++ != '\0') ;} while (*ep++ != '\0');ep--;}if (((int)ep + NVRAM_SIZE - (int)ep) < (envlen + 1)) {  //是否越界//free(nvramsecbuf);   //不再修改flashreturn (0);  /* Bummer! */}/**  Special case heaptop must always be first since it*  can change how memory allocation works.*/if (strcmp("heaptop", name) == 0) {  //如果是heaptopbcopy(nvrambuf + 2, nvrambuf + 2 + envlen,ep - nvrambuf + 1);  //要放在最前面，把数据向后移动ep = nvrambuf + 2;   //填入heaptop 的数据while (*name != '\0') {*ep++ = *name++;}if (value != NULL) {*ep++ = '=';while ((*ep++ = *value++) != '\0') ;} else {*ep++ = '\0';}} else {   //如果不是heaptop，就直接填吧while (*name != '\0') {*ep++ = *name++;}if (value != NULL) {*ep++ = '=';while ((*ep++ = *value++) != '\0') ;} else {*ep++ = '\0';}*ep++ = '\0';   /* End of env strings */}}cksum(nvrambuf, NVRAM_SIZE, 1);    //最后计算校验和return 1;
}//#if 1  //modify by zhaozhi 2022-03-08
int tgt_setenv(char *name, char *value)
{char *ep;int envlen;char *nvrambuf;char *nvramsecbuf;int ret = 0;
#ifdef NVRAM_IN_FLASHchar *nvram;
#endif/* Non permanent vars. */if (strcmp(EXPERT, name) == 0) {return (1);}/* Calculate total env mem size requiered */envlen = strlen(name);   //变量名的长度if (envlen == 0) {return (0);}if (value != NULL) {envlen += strlen(value);  //加上对应值的长度}envlen += 2;       /* '=' + null byte */  //多用两个字节if (envlen > 255) {                  //超出范围return (0);    /* Are you crazy!? */}//printf("2022-03-08 envlen = %d\n",envlen);/* Use first defined flash device (we probably have only one) */
#ifdef NVRAM_IN_FLASHnvram = (char *)(tgt_flashmap())->fl_map_base;    //0xbfc00000/* Deal with an entire sector even if we only use part of it */nvram += NVRAM_OFFS & ~(NVRAM_SECSIZE - 1);   //0xbfcff000
#endif/* If NVRAM is found to be uninitialized, reinit it. */if (nvram_invalid) {  //0 表示已经初始化了printf("2022-03-08 tgt_setenv nvram_invalid\n");nvramsecbuf = (char *)malloc(NVRAM_SECSIZE);if (nvramsecbuf == 0) {printf("Warning! Unable to malloc nvrambuffer!\n");return (-1);}
#ifdef NVRAM_IN_FLASHmemcpy(nvramsecbuf, nvram, NVRAM_SECSIZE);
#endifnvrambuf = nvramsecbuf + (NVRAM_OFFS & (NVRAM_SECSIZE - 1));memset(nvrambuf, -1, NVRAM_SIZE);nvrambuf[2] = '\0';nvrambuf[3] = '\0';cksum((void *)nvrambuf, NVRAM_SIZE, 1);printf("Warning! NVRAM checksum fail. Reset!\n");
#ifdef NVRAM_IN_FLASH#ifdef BOOT_FROM_NANDmemcpy(nvram, nvramsecbuf, NVRAM_SECSIZE);//update_env_to_nand( nvram, nvramsecbuf,NVRAM_SECSIZE);update_rom_to_nand_1block(nvram,(char *)(tgt_flashmap())->fl_map_base);
#elseif (fl_erase_device(nvram, NVRAM_SECSIZE, FALSE)) {printf("Error! Nvram erase failed!\n");free(nvramsecbuf);return (-1);}if (fl_program_device(nvram, nvramsecbuf, NVRAM_SECSIZE, FALSE)) {printf("Error! Nvram init failed!\n");free(nvramsecbuf);return (-1);}
#endif#elsenvram_put(nvramsecbuf);
#endifnvram_invalid = 0;free(nvramsecbuf);}//end if (nvram_invalid)/* Remove any current setting *///tgt_unsetenv(name);    //删除原来的            修改的部分2022-03-08/* Find end of evironment strings */nvramsecbuf = (char *)malloc(NVRAM_SECSIZE);   //分配一片空间 500字节if (nvramsecbuf == 0) {printf("Warning! Unable to malloc nvrambuffer!\n");return (-1);}
#ifndef NVRAM_IN_FLASHnvram_get(nvramsecbuf);
#elsememcpy(nvramsecbuf, nvram, NVRAM_SECSIZE); //把数据都回来
#endifnvrambuf = nvramsecbuf + (NVRAM_OFFS & (NVRAM_SECSIZE - 1));//printf("2022-03-08 nvrambuf = %p nvramsecbuf = %p\n",nvrambuf,nvramsecbuf);/* Etheraddr is special case to save space */
#if 1               /*added by tangyt */if (strcmp("activecom", name) == 0) {activecom = strtoul(value, 0, 0);printf("set activecom to com %d\n", activecom);} else if (strcmp("em_enable", name) == 0) {em_enable = strtoul(value, 0, 0);printf("set em_enable to com %d\n", em_enable);} else
#endifif (strcmp("ethaddr", name) == 0) {   //如果名字是"ethaddr"char *s = value;int i;int32_t v;for (i = 0; i < 6; i++) {gethex(&v, s, 2);hwethadr[i] = v;s += 3;   /* Don't get to fancy here :-) */}}else {  //不是"ethaddr"   //修改的部分！！！！2022-03-08if(0 == tgt_setenv_inmem(name,value,envlen,nvrambuf)){printf("tgt_setenv_inmem return 0\n");return 0;}}//cksum(nvrambuf, NVRAM_SIZE, 1);
#ifdef NVRAM_IN_FLASHbcopy(&activecom, &nvrambuf[ACTIVECOM_OFFS], 1);   //这里不包括checksum? 有问题bcopy(&em_enable, &nvrambuf[MASTER_BRIDGE_OFFS], 1);
#endifbcopy(hwethadr, &nvramsecbuf[ETHER_OFFS], 6);
#ifdef NVRAM_IN_FLASH#ifdef BOOT_FROM_NANDmemcpy(nvram, nvramsecbuf, NVRAM_SECSIZE);//update_env_to_nand( nvram, nvramsecbuf,NVRAM_SECSIZE);update_rom_to_nand_1block(nvram, (char *)(tgt_flashmap())->fl_map_base);
#elseif (fl_erase_device(nvram, NVRAM_SECSIZE, FALSE)) {printf("Error! Nvram erase failed!\n");free(nvramsecbuf);return (0);}if (fl_program_device(nvram, nvramsecbuf, NVRAM_SECSIZE, FALSE)) {printf("Error! Nvram program failed!\n");free(nvramsecbuf);return (0);}
#endif#else  // ifdef NVRAM_IN_FLASH 不执行nvram_put(nvramsecbuf);
#endiffree(nvramsecbuf);return (1);
}

有两个地方修改：

1. 删除了原来调用删除环境变量的操作 tgt_unsetenv(name); 这个函数会操作flash（从flash读数据到内存，在内存中删除数据，擦除flash，再把修改后的数据编程到flash），就没必要了。

2. 调用了我自己写的一个函数 tgt_setenv_inmem(name,value,envlen,nvrambuf)，在这个函数中先去从flash读数据到内存，在内存中删除原有的，然后加入新的。再计算一次校验和，擦除flash，再把修改后的数据编程到flash，这样对flash的操作就只有一次读，一次擦除和一次写操作。

目前测试了，对于加入一个新的环境变量，删除一个有的环境变量，修改一个存在的环境变量，都能正常工作了。

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