[Arm-netbook] http://rhombus-tech.net/allwinner_a10/a10_boot_process/

[Tom Cubie]

在 2011年12月28日星期三，Henrik Nordström <henrik at henriknordstrom.net> 写道：
> Sorry for topposting. Posted from my mobile.
>
> boot0 and onwards is clearly loaded from the boot media/flash. boot0
first sets up the basic hardware configuration so DRAM memory access etc
works. Then loads boot1 from somewhere into ram.
>
> I would think boot1 is really the second part of boot0, after the first
page.
>
> Only BROM is in ROM. Plus bootstrap pins telling brom if it should look
for sdcard, nand or usb fel mode for recovery.
You are right. But there is only one pin to determine go to fel or not, no
other pins to decide which media to boot from. It just try to boot from
sdcard0, if failure, try NAND, then try sdcard2, then try spi nor. If
nothing to boot, go to fel.
>
> It would be excellent if boot0 & boot1 sources can be published, or at
minimum the boot0 hardware header specification and checksum method,
allowing boot0 to be reconfigured in an open & portable manner. If sources
can not be published (but hardware header can) then at least boot0&1
binaries licensed under a permissible license allowing unlimited
redistribution of both original and modified versions.
Exactly.
>
> My understanding is that boot.axf (and boot0.axf) is u-boot or similar
mostly generic bootloader, with all hardware setup separated out in boot0/1.
>
> Many other SoC uses similar boot method, with a master boot record from
boot media configuring basic hardware and then loading the rest.
>
> If boot0/1 can not be published to an acceptable degree then the other
option for this project to be viable is to add a small external serial prom
for these (i assume A10 can also load boot0 via SPI?). But that adds to the
bom and looses a bit of the flexibility of the product and may not be
suitable for the mass market target. But should be possible to use same
board just leave the rom position unpopulated.
>
> Regards
> Henrik
>
> ----- Ursprungsmeddelande -----
>> tom, you're a star - thank you for creating the boot process page.
>>
>> question: boot.axf, its source code is available?
>>
>> if so, then the a10 boot process isn't actually "closed", it's more
>> "standard practice".   those boot0 and boot1 bits, they're ROM'd aren't
>> they?   that's considered to be ok.
>>
>> l.
>>
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>
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-- 
Keep simple, stay foolish.
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