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 Boot from USB: no linux kernel found 
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Joined: 21 Feb 2008, 14:54
Posts: 3
Post Boot from USB: no linux kernel found
Hi to all... I'm posting this in case it helps someone. Although it's not a BIG issue, it's something if you face, perhaps you won't know how to solve it.

I downloaded SystemRescueCd 0.4.3, and used the instructions under install SystemRescueCd on an USB stick to install it from Windows.

After solving some little issues, I made the USB load the syslinux bootloader, but at this stage, the "boot:" prompt was displayed without any additional text.
Trying to boot default, or write down "vmlinuz2" or "rescuecd" or any other thing left to "linux kernel not found" message. I checked and re-checked the file locations, and nothing.

I also tried http://www.sysresccd.org/Howto_install-usb-stick and nothing

Then I remembered something: all linux bootloaders I know (I mostly know grub) have a limitation: they only see things in the first XXMB of the disk. I don't remember the exact number, but I think it's 128MB.

The manual says

Quote:
1. Copy "syslinux/syslinux.cfg" to the root of the USB device
2. Copy "sysrcd.dat" to the root of the USB device
3. Copy files in the "isolinux" directory to the root of the USB device
4. Copy the "bootdisk" directory to the root of the USB device


I think this manual was done in times in which SystemRescueCD was about 120MB size, but now "sysrcd.dat" is 140MB size. If you copy first this file and AFTER that the kernel images and initrd images, these will drop out of the range of the boot loader, so I modified the procedure to do the same but in different order

1. Copy isolinux files
2. Copy bootdisk files
3. Copy syslinux.cfg and sysrcd.dat
4. syslinux -ma e: (my pendrive was at e:)

Voilá... the disk booted perfect!!!!

Hope this helps someone :) see you around.


21 Feb 2008, 15:30
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Site Admin

Joined: 17 Jul 2003, 09:44
Posts: 2700
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Thanks for your contrib, I updated the page about USB sticks.


21 Feb 2008, 20:32
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Joined: 28 Feb 2008, 02:45
Posts: 1
Post Re: Boot from USB: no linux kernel found
myrddraal wrote:
Then I remembered something: all linux bootloaders I know (I mostly know grub) have a limitation: they only see things in the first XXMB of the disk. I don't remember the exact number, but I think it's 128MB.


Really! I have a 32GB root partition that is also boot partition. I routinely modify the kernel boot files and I never had your issue. Of course, this is on a hard disk. I don't think grub is the reason for your problem, but most likely your motherboard BIOS!


28 Feb 2008, 02:52
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Joined: 21 Feb 2008, 14:54
Posts: 3
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Well, perhaps you're right, I'm not a boot expert, and perhaps I misunderstood BIOS limitations with bootloader limitations. What I'm pretty sure is that it affects directly on the bootloader.

What I know is that boot partitions that are not small and at the begining of the disk, keep getting problems even when BIOS improved a lot their capabilities in the last years.

My BIOS is not so old, my laptop is 1.5 years old, so I should expect to find these problems in many systems. It's better to work in such a way that all the machines work. This is the reason, I think, most Linux distros has this /boot partition of 128MB at the very beginning of the disk as a default partition configuration, and they recommend leave it that way.

That's what I tried to figure in the post, and perhaps the fact that I had only 2 minutes to write made it a little confusing.

Thanks for your answer


28 Feb 2008, 14:52
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Joined: 29 Feb 2008, 04:53
Posts: 7
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http://www.sysresccd.org/Howto_install-usb-stick
and
http://www.sysresccd.org/Sysresccd-manu ... _USB-stick
Don't have the same order I think one guide should be changed or one guide should be removed/merged

As long as the .dat file goes 4th and the other three are at the start isn't that fine?
I'm presuming the .dat file isn' read until the full OS kicks in.

Anyhoo

I've got a bunch of personal files on my usb stick and I think I'm having the same problem.

If I mv all the files back to my pc then mv the 4 imortant files back to the usb them mv my personal files back to the usb will the 4 now be at the front?

Or do i have to reformat before moving back or somting?

What did you do myrddraal?

I don't know if this depends on how fat works or it its how usbflash works or what?

Thanks :)


29 Feb 2008, 05:25
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Joined: 21 Feb 2008, 14:54
Posts: 3
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Hi... sabgenton.

I reformatted to be sure, if you can, it won't take to much to do it and you'll be sure to store the linux kernel and ramdisk at the very beginning.

Usually, OS works on the filesystem in such a way that stores the files in the closest position to the beginning of the disk that they find available, roughly speaking, AFAIK.

So if you move the files like you suggested, most probabily it will work, and your kernel and initrd will be at the beginning of the disk. If you don't want to format, try it, and if it doesn't work just format.

And yes, the .dat file is not read until the kernel and initrd is loaded, this is one of the very first things the machine does when you boot, just after loading the boot loader.


29 Feb 2008, 13:20
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Joined: 29 Feb 2008, 04:53
Posts: 7
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Oh silly me i copyed the isolinux folder instead of the files! mabey I had no problem in the first place!
thanks for your help!


29 Feb 2008, 14:20
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