# Different USB booting behavior on identical laptops

## grant123

I have two Dell XPS 13 laptops that must be nearly identical as far as hardware.  I built a bootable USB stick from the latest version of sysresccd.  One of the laptops boots to it no problem and the other gives me this:

```
!! cannot find /sysrcd.dat on devices

!! running a mini shell (cannot complete the boot process)

/bin/sh:  can't access tty; job control turned off
```

What could be causing one to fail if the other works?

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## skiwarz

how far into the boot process does it get? ie does it start loading the kernel? Or does it not even get to the bootloader?

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## grant123

Unfortunately I'm not sure.  I'm troubleshooting this in a timezone 9 hours away so relaying info is slow.

This is with sysresccd-4.7.2.  The sysresccd I tried previously was 4.4.1 and I never ran into this issue.

Could it be a USB config issue in the BIOS?

I know some of these laptops have two USB 3.0 ports and some have one USB 3.0 port and one USB 2.0 port.  Could that be related?

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## skiwarz

That would be my first guess. If the hardware is all the same, then it's probably bios. Go through and copy all the bios setting exactly like they are in the good machine. See what happens, I guess?

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## khayyam

 *grant123 wrote:*   

> What could be causing one to fail if the other works?

 

grant123 ... it may not be the laptops at all, not all flash disks are created equal, and so unless the USB Flash were the same you can't asume the particular boot sticks are good (fake flash can make it seem the write was successful).

best ... khay

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## grant123

Hi Khay, it's the same USB stick.  There are 2 laptops and 1 USB stick.

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## Buffoon

Basically the sequence is like this. BIOS/Firmware boots the boot drive, bootloader loads kernel, kernel mounts root filesystem. In order to do the last step kernel must have correct drivers to access the hardware with root partition on it. In case when kernel does not have correct USB driver to access the USB stick you will end up with kernel panic or rescue shell, depending on your initrd.

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## pilla

Some bios have options for setting USB in legacy modes. Check for it.

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## grant123

All of the USB BIOS config between the laptop that works and the one that doesn't work is the same.  The laptop that doesn't work is on BIOS A09 and the latest is A10 so I'm going to try updating that.  The laptop that does work is on A06 so it's probably a longshot.

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## khayyam

 *grant123 wrote:*   

> Hi Khay, it's the same USB stick. There are 2 laptops and 1 USB stick.

 

hey ... I see, the 9hr timezone seperation made me think the two laptops, and so USB sticks, were some distance from each other. 

 *grant123 wrote:*   

> All of the USB BIOS config between the laptop that works and the one that doesn't work is the same.  The laptop that doesn't work is on BIOS A09 and the latest is A10 so I'm going to try updating that.  The laptop that does work is on A06 so it's probably a longshot.

 

Well, I updated a D820 to A10 just the other day and I can boot sysresccd (on a USB stick) no problem. BTW, when I updated mine I noticed dell provide a changelog for the BIOS updates so before you make yourself a FreeDOS/BIOS update bootdisk I'd see if there might be any clue there.

The only other thing I could think of otherwise is a bad ram chip, if you have both a top and bottom slot perhaps trying removing one, and or swaping them out with the 'good' machines ram ... just a thought.

best ... khay

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## grant123

It appears to be a flaky USB port.  The same port is having trouble consistently recognizing a USB network adapter which needs to be unplugged/replugged several times to be noticed.  That trick doesn't seem to work for booting the USB stick though.

BTW, both ports are USB 3.0.

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## pilla

 *grant123 wrote:*   

> It appears to be a flaky USB port.  The same port is having trouble consistently recognizing a USB network adapter which needs to be unplugged/replugged several times to be noticed.  That trick doesn't seem to work for booting the USB stick though.
> 
> BTW, both ports are USB 3.0.

 

That's some hard debugging... Send it back to guarantee, if you can.

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## grant123

Out of 12 of these laptops, we found 2 with this same problem on the left USB port.  The Dell XPS 13 has several variants but 9 of these are the L322X variant and those with a bad USB port are L322X so that's 2/9 so I don't think it's by design.  Also worth mentioning is the L321X variant will not boot from the left USB port at all (3/3), even on the latest BIOS (A08).

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## krinn

 *grant123 wrote:*   

> those with a bad USB port are L322X so that's 2/9 so I don't think it's by design.

 

they could both use L322X but with different capacitors... it's still a design trouble, worst of all, hardware design failure are hard or impossible to fix by software, so no bios update will help.

In many countries, design flaw lead a force warranty, no matter the age of the product.

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