diff options
Diffstat (limited to 'qemu/roms/u-boot/doc/README.enetaddr')
| -rw-r--r-- | qemu/roms/u-boot/doc/README.enetaddr | 116 |
1 files changed, 0 insertions, 116 deletions
diff --git a/qemu/roms/u-boot/doc/README.enetaddr b/qemu/roms/u-boot/doc/README.enetaddr deleted file mode 100644 index 1eaeaf941..000000000 --- a/qemu/roms/u-boot/doc/README.enetaddr +++ /dev/null @@ -1,116 +0,0 @@ ---------------------------------- - Ethernet Address (MAC) Handling ---------------------------------- - -There are a variety of places in U-Boot where the MAC address is used, parsed, -and stored. This document covers proper usage of each location and the moving -of data between them. - ------------ - Locations ------------ - -Here are the places where MAC addresses might be stored: - - - board-specific location (eeprom, dedicated flash, ...) - Note: only used when mandatory due to hardware design etc... - - - environment ("ethaddr", "eth1addr", ...) (see CONFIG_ETHADDR) - Note: this is the preferred way to permanently store MAC addresses - - - ethernet data (struct eth_device -> enetaddr) - Note: these are temporary copies of the MAC address which exist only - after the respective init steps have run and only to make usage - in other places easier (to avoid constant env lookup/parsing) - - - struct bd_info and/or device tree - Note: these are temporary copies of the MAC address only for the - purpose of passing this information to an OS kernel we are about - to boot - -Correct flow of setting up the MAC address (summarized): - -1. Read from hardware in initialize() function -2. Read from environment in net/eth.c after initialize() -3. The environment variable will be compared to the driver initialized - struct eth_device->enetaddr. If they differ, a warning is printed, and the - environment variable will be used unchanged. - If the environment variable is not set, it will be initialized from - eth_device->enetaddr, and a warning will be printed. -4. Program the address into hardware if the following conditions are met: - a) The relevant driver has a 'write_addr' function - b) The user hasn't set an 'ethmacskip' environment variable - c) The address is valid (unicast, not all-zeros) - -Previous behavior had the MAC address always being programmed into hardware -in the device's init() function. - -------- - Usage -------- - -If the hardware design mandates that the MAC address is stored in some special -place (like EEPROM etc...), then the board specific init code (such as the -board-specific misc_init_r() function) is responsible for locating the MAC -address(es) and initializing the respective environment variable(s) from it. -Note that this shall be done if, and only if, the environment does not already -contain these environment variables, i.e. existing variable definitions must -not be overwritten. - -During runtime, the ethernet layer will use the environment variables to sync -the MAC addresses to the ethernet structures. All ethernet driver code should -then only use the enetaddr member of the eth_device structure. This is done -on every network command, so the ethernet copies will stay in sync. - -Any other code that wishes to access the MAC address should query the -environment directly. The helper functions documented below should make -working with this storage much smoother. - ---------- - Helpers ---------- - -To assist in the management of these layers, a few helper functions exist. You -should use these rather than attempt to do any kind of parsing/manipulation -yourself as many common errors have arisen in the past. - - * void eth_parse_enetaddr(const char *addr, uchar *enetaddr); - -Convert a string representation of a MAC address to the binary version. -char *addr = "00:11:22:33:44:55"; -uchar enetaddr[6]; -eth_parse_enetaddr(addr, enetaddr); -/* enetaddr now equals { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55 } */ - - * int eth_getenv_enetaddr(char *name, uchar *enetaddr); - -Look up an environment variable and convert the stored address. If the address -is valid, then the function returns 1. Otherwise, the function returns 0. In -all cases, the enetaddr memory is initialized. If the env var is not found, -then it is set to all zeros. The common function is_valid_ether_addr() is used -to determine address validity. -uchar enetaddr[6]; -if (!eth_getenv_enetaddr("ethaddr", enetaddr)) { - /* "ethaddr" is not set in the environment */ - ... try and setup "ethaddr" in the env ... -} -/* enetaddr is now set to the value stored in the ethaddr env var */ - - * int eth_setenv_enetaddr(char *name, const uchar *enetaddr); - -Store the MAC address into the named environment variable. The return value is -the same as the setenv() function. -uchar enetaddr[6] = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55 }; -eth_setenv_enetaddr("ethaddr", enetaddr); -/* the "ethaddr" env var should now be set to "00:11:22:33:44:55" */ - - * the %pM format modifier - -The %pM format modifier can be used with any standard printf function to format -the binary 6 byte array representation of a MAC address. -uchar enetaddr[6] = { 0x00, 0x11, 0x22, 0x33, 0x44, 0x55 }; -printf("The MAC is %pM\n", enetaddr); - -char buf[20]; -sprintf(buf, "%pM", enetaddr); -/* the buf variable is now set to "00:11:22:33:44:55" */ |