Date: Sun, 8 Jun 2008 08:51:36 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Alan Cox <alc@cs.rice.edu> Cc: hackers@freebsd.org Subject: Re: Increasing KVM on amd64 Message-ID: <20080608055136.GT94309@deviant.kiev.zoral.com.ua> In-Reply-To: <484B709F.1070503@cs.rice.edu> References: <484B20E7.2040009@cs.rice.edu> <20080608052653.GS94309@deviant.kiev.zoral.com.ua> <484B709F.1070503@cs.rice.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
[-- Attachment #1 --] 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: > >`-mcmodel=kernel' > >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. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAkhLc2cACgkQC3+MBN1Mb4gNZQCgwQvQcQtvW/sIzRZ6aoFybfQS A3cAn1x0joGdGbEwq7mRBCbCTizeED1h =t2MU -----END PGP SIGNATURE-----
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20080608055136.GT94309>