Date: Sun, 8 Jun 2008 08:26:53 +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: <20080608052653.GS94309@deviant.kiev.zoral.com.ua> In-Reply-To: <484B20E7.2040009@cs.rice.edu> References: <484B20E7.2040009@cs.rice.edu>
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--qZLIv6EoKi7YuaSc Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Jun 07, 2008 at 06:59:35PM -0500, Alan Cox wrote: > You can download a patch from=20 > http://www.cs.rice.edu/~alc/amd64_kvm_6GB.patch that increases amd64's=20 > kernel virtual address space to 6GB. This patch also increases the=20 > default for the kmem map to almost 2GB. I believe that kernel loadable= =20 > modules still work. However, I suspect that mini-dumps are broken. The amd64 modules text/data/bss virtual addresses are allocated from the=20 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=3Dkernel' 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. >=20 > I don't plan on committing this patch in its current form. Some of the= =20 > changes are done in a hackish way. I am, however, curious to hear=20 > whether or not it works for you. >=20 > Alan --qZLIv6EoKi7YuaSc Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAkhLbZwACgkQC3+MBN1Mb4i9BgCgtmAc3vZy0zyesiRVFBIcZ1Qs pLEAoM5TMKupttnKAQlmx6Iam0tEb4ND =79Y/ -----END PGP SIGNATURE----- --qZLIv6EoKi7YuaSc--
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