Increasing KVM on amd64
kostikbel at gmail.com
Sun Jun 8 05:51:43 UTC 2008
On Sun, Jun 08, 2008 at 12:39:43AM -0500, Alan Cox wrote:
> Kostik Belousov wrote:
> >On Sat, Jun 07, 2008 at 06:59:35PM -0500, Alan Cox wrote:
> >>You can download a patch from
> >>http://www.cs.rice.edu/~alc/amd64_kvm_6GB.patch that increases amd64's
> >>kernel virtual address space to 6GB. This patch also increases the
> >>default for the kmem map to almost 2GB. I believe that kernel loadable
> >>modules still work. However, I suspect that mini-dumps are broken.
> >The amd64 modules text/data/bss virtual addresses are allocated from the
> >kernel_map (link_elf_obj.c, link_elf_load_file). Now, the lower end
> >of the kernel_map is top-6Gb.
> >Kernel code (both kernel proper and modules) is compiled for "kernel memory
> >model", according to the gcc info:
> >Generate code for the kernel code model. The kernel runs in the
> >negative 2 GB of the address space. This model has to be used for
> >Linux kernel code.
> >I suspect we have a problem there.
> The change to link_elf_obj.c is supposed to ensure allocation of an
> address in the upper 2GB of the kernel map for the module.
Ah, I overlooked it, sorry.
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