On 2015-01-25 11:44, Brian May wrote:

I have a i7 based HP computer here that until recently was booting Linux and Windows just fine. According to the user, it stopped working after updating the graphics drivers under Windows.

Do you have access to the PC in person? If not, I'd recommend getting access.

* Selecting any Linux kernel from grub, results in the computer freezing immediately after loading the kernel (no time to initialize the kernel), with a black screen.

Have you tried booting without the 'quiet' option on the kernel command-line? Also have you tried blacklisting the 'nouveau' driver? I forget exactly how to do this in Debian but I'm sure it's straightforward. I have a very similar-sounding HP computer (HP ENVY Phoenix 810-110a) that also came with a GeForce GT 640 which the nouveau driver is _completely_ broken in. Basically I get to the kernel message "fb: switching to nouveaufb from EFI VGA" and nothing proceeds beyond that point. (I also boot in UEFI mode.) My solution was either to use the NVIDIA proprietary driver (most distro packages for the binary driver will blacklist nouveau as a side-effect) or to use the integrated Intel graphics instead.

Brian May wrote:

Hello,

I have a i7 based HP computer here that until recently was booting Linux and Windows just fine. According to the user, it stopped working after updating the graphics drivers under Windows.

Anyway the symptoms are:

* Grub loads fine. * Selecting any Linux kernel from grub, results in the computer freezing immediately after loading the kernel (no time to initialize the kernel), with a black screen. * Selecting memtest results in similar problems. * Same thing happens booting from rescue items in grub menu. No extra debugging information. * Keyboard unresponsive after crash. Caps-lock, num-lock, and Ctrl-Alt-Delete don't work. * Booting windows works fine. * Booting Debian live CD image on USB works fine. It has the standard Debian wheezy kernel, 3.2.0-4-amd64, which is the same as one of the options I was attempting to boot from the hard disk. * Power cycling is the only way to un-crash the system.

Extra facts: * It is a Nvidia GeForce GT 640 based graphics card * The live CD does not use grub. * Debian/wheezy based system with extra kernels installed from Debian backports. * The dog barking does not make any difference what so ever. * Nvidia closed source drivers not installed (not that I see this making any difference, as the kernel doesn't appear to be started when it crashes) * This is a UEFI boot system, with secure boot turned off.

Have tried installing another kernel after booting live CD, and reinstalling grub, however nothing changed.

Have run memtest from live CD, no errors reported.

Only thing I can think of is that the update of the graphics drivers under Windows has updated the graphics card firmware breaking boots from the version of Grub in Debian stable/wheezy. Does this even make sense?

Any other ideas?

Not clear to me that the above, eliminated possibility that, the Nvidia GeForce GT 640 Windows driver update; some how corrupted the installed Debian/wheezy driver ? regards Rohan McLeod

Thanks -- Brian May <brian@microcomaustralia.com.au <mailto:brian@microcomaustralia.com.au>>

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On 25 January 2015 at 11:44, Brian May <brian@microcomaustralia.com.au> wrote:

I have a i7 based HP computer here that until recently was booting Linux and Windows just fine. According to the user, it stopped working after updating the graphics drivers under Windows.

I finally got it working again. I was forgetting that you can't (re)install grub-efi unless you are booted using EFI first. As my live boot CD was legacy boot not EFI, that rendered my initial attempts to reinstall grub invalid. (sometimes it will tell you, curiously not after booting from this live CD). Anyway, I installed the USB image of rEFInd ( http://www.rodsbooks.com/refind/) onto a USB device, booted from it using EFI. It immediately found a number of boot options, including my existing grub setup. I booted from this, then selected by installed Linux image. Curiously all this worked. Once booted, I run as root: grub-install /dev/sda7 update-grub Now everything works again[1]. I am still a bit puzzled what happened, maybe the windows update did something to stuff up my grub. At least it is working now. Thanks for everyone trying to assist. Notes [1] Actually memtest still is broken, am suspecting that the images provided with Debian wheezy don't work with EFI. -- Brian May <brian@microcomaustralia.com.au>

Brian May writes:

[computer no work]

AFAICT nobody has asked yet: So the local keyboard/video are borked. But: does it issue a DHCP request? Can you ping, SSH it? If only the local KVM stack is borked, you might be able to poke around in the running system. Also there is netconsole, but that's probably not helpful in this case.