Messages in this thread | | | Subject | Re: Patch to reorder functions in the vmlinux to a defined order | From | Fernando Luis Vazquez Cao <> | Date | Fri, 24 Feb 2006 11:44:15 +0900 |
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On Thu, 2006-02-23 at 15:26 -0500, Dave Jones wrote: > On Thu, Feb 23, 2006 at 09:13:24PM +0100, Rene Herman wrote: > > Linus Torvalds wrote: > > > > >If you want to boot a 4MB machine with the suggested patch, you'd > > >have to enable CONFIG_EMBEDDED (something you'd likely want to do > > >anyway, for 4M machine), and turn the physical start address back > > >down to 1MB. > > > > Okay. I suppose the only other option is to make "physical_start" a > > variable passed in by the bootloader so that it could make a runtime > > decision? Ie, place us at min(top_of_mem, 4G) if it cared to. I just > > grepped for PHYSICAL_START and this didn't look _too_ bad. > > > > I'm out of my league here though -- if I remember correctly from some > > reading of the early bootcode I once did, the kernel set up some > > temporary tables first to only cover the first few MB? If so, then I > > guess it would be a significant change. > > > > Seems a bit cleaner though than just hardcoding the address. > > the kdump people were looking at making the kernel runtime relocatable > at one point, which with my distro-vendor hat on, would be useful > as it'd mean we could use the same kernel image for normal boot, and > also for the 'kdump kernel' The mkdump team has accomplished this ...
> (Right now, we ship another set of > kernels for each arch with a different PHYSICAL_START). ... so that we do not need to hard-code PHYSICAL_START. The dump capture kernel is able to run from any memory address the host kernel reserves for it. The are some limitations though:
- i386: the second kernel has to be loaded in low memory - x86_64: the second kernel has to be loaded below 1GB (we are working to move this limit to 4GB)
> (You wouldn't believe how much grief we get from the installer folks > for adding another set of kernel images to the ISOs). > > I think that work stalled a while back though.
The mkdump team has been using runtime relocatable kernels for two years and we are currently working on porting this functionality to kdump. I was wondering if it would be accepted mainstream.
Regards,
Fernando
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