Comment 0 for bug 241076

According to upstream, the software IO TLB aperture is supposed to default to 2MB on machines under 2GB and to 64MB on machines over 2GB of RAM. Under dapper and edgy, we saw this on our servers:

[ 0.525506] Software IO TLB enabled:
[ 0.525507] Aperture: 64 megabytes

Under hardy, we see the following:

[ 0.291228] Software IO TLB enabled:
[ 0.291230] Aperture: 2 megabytes

This leads to kernel panics when we attempt to do anything reasonable complex like, oh, run apt-get or vim.

Amending grub/menu.list's xenkopt line to the following fixes it for us:

# xenkopt=console=tty0 swiotlb=64

I'm not sure if the kernel's method for counting total RAM has changed just enough to throw this "how big should our SW TLB be?" calculation off, or if something else has gone wrong, but the current default is pretty clearly "wrong", as it doesn't work at all for anything more than logging in and running nano.