On 09/06/2012 07:09 AM, Khalid Aziz wrote: > This will evaluate only the first line in systab. I do not believe you > are guaranteed to see ACPI20= or ACPI= in the first line. Here is the > systab file from my machine: > > MPS=0xf4cf0 > ACPI20=0xcac3e000 > ACPI=0xcac3e000 > SMBIOS=0xcac4cf98 > > We need to parse all the lines in systab. Thanks for the reporting, will address this in the update patch > I think running a kexec/kdump kernel with "noefi" is not a good idea. > Today kernel makes very little use of UEFI run time services but this > might change shortly. I have already seen ideas being proposed to use > UEFI variables to store kernel panic information which would require > accessing UEFI runtime services. If the kdump kernel runs into a panic, > it would be good to be able to use UEFI variables to store some sort of > tombstone. We might also start using UEFI runtime clock services one of > these days especially now that all PCs soon will have UEFI due to > Windows 8 requirements. There might be other ways to deal with EFI > virtualization issue. I have solved it on a custom ia64 kernel by > passing the kexec'd kernel a "kexec_reboot" on command line, although I > wouldn't recommend that approach as a general approach. Creating a new > kernel command line parameter just to tell the kernel to not virtualize > EFI sounds excessive. May be we can come up with a different way to tell > a kexec/kdump kernel to not virtualize EFI, like create a new signature, > for example "EL32_KEXEC" and "EL64_KEXEC", for > boot_params.efi_info.efi_loader_signature which tells the kexec/kdump > kernel to enable EFI but skip the step of virtualizing it. More work > will be needed to make this work, for example pass the EFI runtime > service memory map from one kernel to the next so we keep it mapped in > exact same spot, and other similar mapping issues. > I'm not so familiar with uefi detail, is the virtualization issue mean "virtual mode" of efi? From my understanding for kdump kernel I would vote for not interacting with bios at all. We have use "noefi" for long time by passing it to 2nd kernel while kexecing. I prefer to do this way until we have to switch to other approach. -- Thanks Dave
