[U-Boot] [PATCH v7 00/15] SiFive FU540 Support

[Alexander Graf]

On 02/12/2019 11:12 AM, Bin Meng wrote:
> On Tue, Feb 12, 2019 at 5:09 PM Andreas Schwab <schwab at suse.de> wrote:
>> On Feb 12 2019, Bin Meng <bmeng.cn at gmail.com> wrote:
>>
>>> On Tue, Feb 12, 2019 at 4:34 PM Andreas Schwab <schwab at suse.de> wrote:
>>>> On Feb 12 2019, Anup Patel <anup at brainfault.org> wrote:
>>>>
>>>>> This is because we don't have place to put U-Boot environment
>>>>> variables as of now on Unleashed board. This will be solved once
>>>>> we have SPI driver and SPI_MMC driver for Unleased board.
>>>> Isn't the MAC part of the initial DT?
>>>>
>>> My understanding is that U-Boot should fixup the DT using the
>>> <ethaddr> environment value, before jumping to Linux.
>> But where does it get the env var from?  Why would it need to modify the
>> MAC?
>>
> The env var is stored in whatever supported media in U-Boot. Not like
> PCI NICs which normally have EEPROM to store pre-flashed MAC address
> by their vendors, for most embedded network controllers in the SoC,
> normally there is no hardware provided mechanism to ensure a unique
> MAC address, instead it relies on software to program one to the
> hardware before bringing it up. In the U-Boot case, it's the <ethaddr>
> env.

Yes, and U-Boot can read it from the DT to populate ethaddr if its upper 
layer does provide a stable MAC address through DT.


Alex