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qi-update-README.patch
Signed-off-by: Andy Green <andy@openmoko.com>
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@ -54,18 +54,30 @@ Booting Heuristics
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Qi has one or more ways to fetch a kernel depending on the device it finds it is
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running on, for example on GTA02 it can use NAND and SD card devices. It goes
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through these device-specific storage devices in order and tries to boot the
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first viable kernel it finds, usually /boot/uImage.bin.
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first viable kernel it finds, usually /boot/uImage-device>.bin for example
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/boot/uImage-GTA02.bin.
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The kernel commandline used is associated with the storage device, this allows
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the correct root= line to be arrived at without any work. The inability to set
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the Qi kernel commandline externally is deliberate, two otherwise identical
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devices differing by the kernel commandline or other "environment" is not good.
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A whole class of bugs and support issues around private bootloader state are
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therefore avoided.
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You can disable a rootfs for consideration for boot if you add a file
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/boot/noboot-<device>, eg, /boot/noboot-GTA02.
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The kernel commandline used is associated with the storage device and partition,
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this allows the correct root= line to be arrived at without any work.
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If no kernel image can be found, Qi falls back to doing a memory test.
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Appending to commandline
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========================
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You can append to the Qi commandline by creating a file /boot/append-<device>,
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eg, /boot/append-GTA02 containing the additional kernel commandline you want.
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This means you can affect the boot per-rootfs, but that if you reimage the
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rootfs you at the same time define what is appeneded. Because these files are
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looked for with the <device> name in them, options can be selected depending on
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the device the rootfs is run on.
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Initrd support
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==============
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@ -76,22 +88,24 @@ memory address in addition to kernel image. The ATAGs are issued accordingly.
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Functional Differences from U-Boot on GTA02
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===========================================
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- Backlight is not enabled until Linux starts after a few seconds
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- kernel loglevel is set to NOT output gobs of text to the screen
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- On GTA02 will ALWAYS boot from uSD if first partition is ext2 and contains
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/boot/uImage.bin, otherwise boots from NAND
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- On GTA03 will ALWAYS boot from uSD second partition if /boot/uImage.bin is
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present otherwise try the third / backup partition
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- Backlight and USB is not enabled until Linux starts after a few seconds
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- No startup splash screen
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- by default there is no boot spew on the LCM
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- On GTAxx boots from first uSD ext2 / 3 partition containing
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/boot/uImage-<devicename>.bin present, eg, /boot/uImage-GTA02.bin, it checks
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first three partitions in turn
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- On GTA01 and 02 if nothing is workable on the SD Card, or it is not present,
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Qi will try to boot from NAND
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- You can disable a partition for boot by creating /boot/noboot-<devicename>,
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eg, /boot/noboot-GTA02, it will skip it and check the next partition
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- Way faster
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- There is no concept of "staying in the bootloader". The bootloader exits to
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Linux as fast as possible, that's all it does.
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- USB is not started until Linux starts around 5 seconds after boot, there is
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no DFU.
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