From mboxrd@z Thu Jan 1 00:00:00 1970 From: tgingold@free.fr Date: Mon, 25 Feb 2008 15:04:29 +0000 Subject: Re: [kvm-ia64-devel] [PATCH 0/4] ia64/xen: paravirtualization of hand written assembly code Message-Id: <1203951869.47c2d8fd37258@imp.free.fr> List-Id: References: <12039094061834-git-send-email-yamahata@valinux.co.jp> In-Reply-To: <12039094061834-git-send-email-yamahata@valinux.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org Quoting Keith Owens : > tgingold@free.fr (on Mon, 25 Feb 2008 13:54:48 +0100) wrote: > >Quoting Keith Owens : > >{...} > >> A combination of options (2) and (3) would work. Have a single source > >> file for the IVT, using conditional macros. Use that source file to > >> build (at least) two copies of the IVT, for native and any virtualized > >> modes. The native copy of the IVT starts at label ia64_ivt in section > >> .text.ivt, as it does now. Any IVT versions for virtualized mode are > >> defined as __cpuinitdata, so they are discarded after boot, unless > >> CONFIG_HOTPLUG_CPU=y. arch/ia64/kernel/head.S copies the relevant > >> virtualized version over ia64_ivt when necessary, before initializing > >> cr.iva. > >> > >> Single source for maintenance. No indirect function overhead at run > >> time. Binary patching at boot time for the right mode. No wasted > >> space in the kernel. > > > >Good idea. The linker script will be slightly more complex however... > > Don't see why the linker script needs to change at all. The existing > native IVT is at label ia64_ivt in section .text.ivt, as it is now. > arch/ia64/kernel/head.S simply overwrites ia64_ivt with 32K of data for > the virtualized IVT, copying from another data area. AFAICT, nothing > in that process requires linker changes. Humm, what about relative jumps ? The object code must be linked as if it were at .text.ivt. I suppose this is doable with OVERLAY in linker script.