Re: [PATCH] xen: increase static dmesg buffer to 64K

[Olaf Hering <olaf@aepfle.de>]

On Mon, Jul 18, Jan Beulich wrote:

> >>> On 17.07.11 at 17:43, Olaf Hering <olaf@aepfle.de> wrote:
> > # HG changeset patch
> > # User Olaf Hering <olaf@aepfle.de>
> > # Date 1310917380 -7200
> > # Node ID c6cade90d47f32e19f529930ba9f9acfa69f065f
> > # Parent  31dd84463eece20bd01c7aee22b52a0c06c67545
> > xen: increase static dmesg buffer to 64K
> > 
> > On large systems the static dmesg buffer will overflow the 16K buffer, early
> > messages are lost. Increase the size to 64K to capture all lines on systems
> > without serial console.
> 
> Please don't - on small systems it's a waste, and on even larger
> systems it still won't help. If anything, the dynamic allocation may
> need to happen earlier. As you probably saw, console_init_postirq()
> already sizes the buffer dependent on the number of CPUs in the
> system.

I think conring_size= should be evaluated very early. Is there a way to
allocate a range of mfns very early which can then be used for the dmesg
buffer?

Olaf