On Mon, Jul 05, 2010 at 02:17:26PM -0700, Mark Knecht wrote:

> On Mon, Jul 5, 2010 at 12:11 PM, Willie Wong <wwong@math.princeton.edu> wrote:

> > On Mon, Jul 05, 2010 at 09:16:14AM -0700, Mark Knecht wrote:

> >> I'm trying to capture the full boot log when booting from the Gentoo

> >> install CD but it seems the buffer isn't deep enough to get the whole

> >> thing. Is there by chance a command line option that will increase the

> >> depth of what's captured by dmesg so that I can get all the way back

> >> to the beginning?

> >

> > pass the following parameter to the kernel on GRUB/LILO:

> >

> > log_buf_len=n

> >

> > where n is a power of two. By default it is 16384. You can change it

> > to 131072 (= 2^17) to get a much larger kernel log ring buffer. If you

> > put in something that is not a power of two, the kernel will ignore

> > the option.

> >

> Thanks for the ideas. I've been trying them but so far no luck.

>

> In my normal booting kernel (on the system hard drive) I did push

> the length up to 18. With that setting dmesg prints all the way back

> to the beginning. However booting the Live CD I hit F1, it shows the

> kernels, so I type

>

> gentoo log_buf_len=18

>

18 is not a power of two.

Why didn't you just try 131072, like I suggested? In maths notation,

n = 2^k

for some natural number k. 18 fails that miserably.

Cheers,

W

--

Willie W. Wong wwong@math.princeton.edu

Data aequatione quotcunque fluentes quantitae involvente fluxiones invenire

et vice versa ~~~ I. Newton