Re: EFI mode after running kexec

[Greg KH <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>]

On Thu, Aug 29, 2013 at 08:18:39AM -0400, Josh Boyer wrote:
> On Wed, Aug 28, 2013 at 10:26 PM, Greg KH <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org> wrote:
> > Hi all,
> >
> > I've been messing with UEFI booting a kernel and then later on, using
> > kexec to boot another kernel, and noticed that the kexec'ed kernel is
> > not really in EFI mode, although the EFI framebuffer seems present and
> > able to be used.
> >
> > Is this to be expected?  I'd think that the EFI framebuffer wouldn't be
> > around anymore.  Odds are this is a BIOS bug, given that the machine I'm
> > using is a really old UEFI mode (i.e. before secure boot mode ever
> > showed up), but should it work this way?
> 
> AFAIK, it's to be expected at this point.  kexec doesn't work as it
> should with UEFI.

How "should" it work?  It seems to boot a kernel just fine, although not
in EFI mode, which makes sense (I had forgotten about the BootServices
stuff.)

> I believe Matthew and/or Matt can elaborate further, but it has to do
> with only being able to call ExitBootServices once and providing
> mappings to the UEFI Runtime services functions.

That makes sense.

thanks,

greg k-h