RE: [BISECTED] 3.19-rc1 regression - kernel does not load in GRUB 0.97 (GRUB Legacy)

From: Пламен Петров
Date: Sun Dec 28 2014 - 02:20:43 EST


> -----Original Message-----
> From: Juergen Gross [mailto:jgross@xxxxxxxx]
> Sent: Saturday, December 27, 2014 3:48 PM
> To: Пламен Петров; linux-kernel@xxxxxxxxxxxxxxx
> Cc: 'Thomas Gleixner'
> Subject: Re: [BISECTED] 3.19-rc1 regression - kernel does not load in GRUB
> 0.97 (GRUB Legacy)
>
> On 12/24/2014 01:28 AM, Пламен Петров wrote:
> > Hello!
> >
> > I use GRUB Legacy bootloader (version 0.97) on a couple machines, and
> > where 3.18.x loads fine, 3.19-rc1 does not.
> >
> > While compiling I used the attached .config file accompanied by "make
> > olddefconfig"
>
> Can you tell me something about the hardware (processor model)?
> You are not booting the system under VMWare by any chance?

As a matter of fact - I am compiling in a VMware Player (6.0.3
build-1895310) virtual machine, boot testing there, and then if everything
is OK, I transfer the monolithic kernel produced on 3 virtual machines that
run on EXSi and 2 actual servers. So along those lines - the failing
3.19-rc1 never saw actual hardware - it was all tested (and bisected) inside
a VM.

>
> Could you try the earlyprintk kernel option (serial or vga)?

Does not help. You see - the kernel never makes it there to print anything.
GRUB just says:

kernel /vmlinuz.test rw root=/dev/sda2 console=ttyS0,9600n8 console=tty0
[Linux-bzImage, setup=0x3c00, size=0x430ec0]

early console in decompress_kernel

Decompressing Linux... Parsing ELF... done.
Booting the kernel.

and it just stays there.

Retyping the above here got me thinking - is early console part of the
kernel?

>
> Can you boot with kernel option "nopat"?

Same as above - kernel command line options do not help, as they never get
into play to even make a difference.

If you need the actual details of my setup or want me to try patches - just
ask.

>
> Juergen
>
> > The bisection I ran points to:
> > bd809af16e3ab1f8d55b3e2928c47c67e2a865d2 is the first bad commit
> > commit bd809af16e3ab1f8d55b3e2928c47c67e2a865d2
> > Author: Juergen Gross <jgross@xxxxxxxx>
> > Date: Mon Nov 3 14:02:03 2014 +0100
> >
> > x86: Enable PAT to use cache mode translation tables
> >

Anyway, thanks to all the devs for their changes in 3.19-rc1 - there is a
huge difference in loading speed in my compile VM: with 3.18.x there is
something like 60 seconds until the VM is up and running; and with 3.19-rc1
(with commit bd809af16e3ab1f8d55b3e2928c4 reverted) - that same machine is
up and running in less than 10 seconds.
So that makes it a 6-fold loading time speedup from just going to 3.19-rc1.
Thanks!
---------------------------------
Plamen Petrov

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