Raspberry Pi: Difference between revisions
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m →Parsing ATAGs: Device trees for later Pis |
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[http://web.archive.org/web/20120605001004/http://www.simtec.co.uk/products/SWLINUX/files/booting_article.html cached version from the Wayback Machine] |
[http://web.archive.org/web/20120605001004/http://www.simtec.co.uk/products/SWLINUX/files/booting_article.html cached version from the Wayback Machine] |
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Note that later Raspberry Pis will pass you a device tree blob instead in R2. ATAGs still can be found at 0x100 - identifiable because they always start with an ATAG_CORE (0x54410001). In comparison, Device Tree is probably far more useful, but is more complex. A device tree starts with the uint32_t 0xd00dfeed '''(big-endian).''' Note the big endian - this applies to all values. ARM defaults to little endian, so you'll probably want to write some endian routines early! |
Note that later Raspberry Pis will pass you a device tree blob instead in R2. ATAGs still can be found at 0x100, if you disable device tree (r2 contains 0x0 in this case) - identifiable because they always start with an ATAG_CORE (0x54410001). In comparison, Device Tree is probably far more useful, but is more complex. A device tree starts with the uint32_t 0xd00dfeed '''(big-endian).''' Note the big endian - this applies to all values. ARM defaults to little endian, so you'll probably want to write some endian routines early! |
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[https://www.devicetree.org/ Device Tree Specification] |
[https://www.devicetree.org/ Device Tree Specification] |
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