Messages in this thread | | | Date | Mon, 21 Mar 2011 14:40:02 +0800 | From | Cong Wang <> | Subject | Re: [Patch] acpi: introduce "acpi_addr=" parameter for kdump |
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Eric, any comments?
Matthew, seems you agree on this patch, may I have your ACK?
Thanks.
于 2011年03月11日 02:50, Matthew Garrett 写道: > On Thu, Mar 10, 2011 at 09:50:28AM -0800, Eric W. Biederman wrote: > >> Move all EFI calls that the kernel does (on x86) into a special section >> of the bzImage that the bootloader can run. This works very well for >> the x86 BIOS and it should also work very well for EFI. Among other >> things by having a special 32bit and a special 64bit section this solves >> the what flavor of EFI problem are we running on problem. > > There's no benefit in calling any EFI methods in the kernel if we have > no intention of making further calls later. If we intent on making > further calls later then this approach doesn't work well. > >> Never perform any EFI calls once the kernel is initialized, last I >> looked all of the EFI calls that were interesting to perform at runtime >> were a subset of what ACPI can do, and ACPI is a easier to deal with >> long term. > > With the exception of reboot, I don't see any overlap between the EFI > runtime services and ACPI. > >> Kexec and kdump can easily pass the gather data from the first kernel to >> the second kernel like we do for the normal bios paramsters today. > > Doing that's not a problem. The real problem is that passing a virtual > map to EFI is a one-shot event. The information we need to provide to > the second kernel isn't a set of parameters - it's the whole memory map, > and we need to depend on the kernel to be able to set up the same map > again. > >> As a fly in the ointment that leaves the question of how do we set EFI >> variables. It is needed functionality when we are installing, and >> occasionally nice to have. But it is a very rare slow path. I would >> isolate the EFI after the kernel has booted to exactly to that one case. >> Either with a special driver or a some flavor of virtualization from >> userspace like we used to do for video card initialization. > > Also capsule updating (not that we implement that at present, but > vendors will want it). But, again, if you want to push this out to some > sort of magic then we can just drop pretty much all of the kernel EFI > support. > >> The current design of EFI in the x86 kernel is crap. We seem to have >> advanced past the early adopter hack anything together to make it work >> stage. So let's stop adding hacks and write something that won't give >> us a long term support problems. > > We're using EFI exactly as it's designed to be used at the moment. The > only problem is that nobody ever thought people would try to do anything > like booting one OS into another OS that has different ideas about > address space layout, but that's a problem with the spec and not our > implementation. >
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