From 4a503bbc81f4f5ac3837c2894dc5cfe98c43fe95 Mon Sep 17 00:00:00 2001 From: Andy Green Date: Fri, 28 Nov 2008 10:16:45 +0000 Subject: [PATCH] qi-update-README.patch Signed-off-by: Andy Green --- qiboot/README | 50 ++++++++++++++++++++++++++++++++------------------ 1 file changed, 32 insertions(+), 18 deletions(-) diff --git a/qiboot/README b/qiboot/README index abff09f..f892773 100644 --- a/qiboot/README +++ b/qiboot/README @@ -54,18 +54,30 @@ Booting Heuristics Qi has one or more ways to fetch a kernel depending on the device it finds it is running on, for example on GTA02 it can use NAND and SD card devices. It goes through these device-specific storage devices in order and tries to boot the -first viable kernel it finds, usually /boot/uImage.bin. +first viable kernel it finds, usually /boot/uImage-device>.bin for example +/boot/uImage-GTA02.bin. -The kernel commandline used is associated with the storage device, this allows -the correct root= line to be arrived at without any work. The inability to set -the Qi kernel commandline externally is deliberate, two otherwise identical -devices differing by the kernel commandline or other "environment" is not good. -A whole class of bugs and support issues around private bootloader state are -therefore avoided. +You can disable a rootfs for consideration for boot if you add a file +/boot/noboot-, eg, /boot/noboot-GTA02. + +The kernel commandline used is associated with the storage device and partition, +this allows the correct root= line to be arrived at without any work. If no kernel image can be found, Qi falls back to doing a memory test. +Appending to commandline +======================== + +You can append to the Qi commandline by creating a file /boot/append-, +eg, /boot/append-GTA02 containing the additional kernel commandline you want. + +This means you can affect the boot per-rootfs, but that if you reimage the +rootfs you at the same time define what is appeneded. Because these files are +looked for with the name in them, options can be selected depending on +the device the rootfs is run on. + + Initrd support ============== @@ -76,22 +88,24 @@ memory address in addition to kernel image. The ATAGs are issued accordingly. Functional Differences from U-Boot on GTA02 =========================================== - - Backlight is not enabled until Linux starts after a few seconds - - - kernel loglevel is set to NOT output gobs of text to the screen - - - On GTA02 will ALWAYS boot from uSD if first partition is ext2 and contains - /boot/uImage.bin, otherwise boots from NAND - - - On GTA03 will ALWAYS boot from uSD second partition if /boot/uImage.bin is - present otherwise try the third / backup partition + - Backlight and USB is not enabled until Linux starts after a few seconds - No startup splash screen + - by default there is no boot spew on the LCM + + - On GTAxx boots from first uSD ext2 / 3 partition containing + /boot/uImage-.bin present, eg, /boot/uImage-GTA02.bin, it checks + first three partitions in turn + + - On GTA01 and 02 if nothing is workable on the SD Card, or it is not present, + Qi will try to boot from NAND + + - You can disable a partition for boot by creating /boot/noboot-, + eg, /boot/noboot-GTA02, it will skip it and check the next partition + - Way faster - There is no concept of "staying in the bootloader". The bootloader exits to Linux as fast as possible, that's all it does. - - USB is not started until Linux starts around 5 seconds after boot, there is - no DFU.