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bootable sdhc cards

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bootable sdhc cards
« on: 17 / April / 2008, 22:37:18 »
in the wiki: Bootable SD card - CHDK Wiki
it shows how to get a bootable sd card setup so the camera (s5 in my case)
can load chdk it says however if you dont see fat12 or fat16 wrong drive etc
well with a sdhc card you tend to see fat32 due to it being over 4gb

after some playing i found if you use fdisk to set the partition to 0x0E (fat16 lba)
and reformat it you can set the sdhc cards to boot
i had looked to see if fat32 specs from wikipedia: File Allocation Table - Wikipedia, the free encyclopedia
could point me to the right place and i gathered that the starting point would be 0x5C for fat32
but it seems the canon firmware doesnt fully understand fat32
and doesnt know to look at 0x5c for boot bit

also for what its worth it seems the camera also doesn't like 1024 byte sector size
so using full space for cards above 4gb might be tricky

wonder if the cameras can use more than 1 partition
or perhaps rather the question can chdk after being loaded from partition 1 redirect
thereafter all files to the 2nd partition where the fat32 partition is

figured a few folks might find this info useful
and since ive never been able to explain cleanly anything i figured i would mention on forums
so someone else if need be can add to wiki


Offline DataGhost

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Re: bootable sdhc cards
« Reply #1 on: 18 / April / 2008, 02:52:08 »
I already gave that some thought a couple of months ago... If you create a 32MB FAT16 partition with CHDK (diskboot.bin) on it and a large (>4GB) FAT32 partition as second (both primary), CHDK will redirect the camera to the second partition automatically. If you change the first partition to 0x05 ('Extended') after putting CHDK on it, Windows will ignore the partition so you can read your pictures even in Windows. More information on this subject and on behaviour of the camera and Windows can be found in Autoboot with 8GB and HDHacker Possibillity.


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