[PATCH] x86: do not enable efi boot for sgi uv machine
Alex Thorlton
athorlton at sgi.com
Fri May 23 12:02:10 PDT 2014
On Fri, May 23, 2014 at 11:19:30AM -0500, Russ Anderson wrote:
> On Fri, May 23, 2014 at 05:54:11PM +0200, Borislav Petkov wrote:
> > On Fri, May 23, 2014 at 09:47:08AM -0400, Dave Young wrote:
> > > Hi,
> > >
> > > Vivek, replying with webmail, sorry for the formatting issue.
> > >
> > > Another way is export the mapping scheme in sysfs. So if kernel boot
> > > with efi=old_map we can detect it as well. OTOH in future there's probably
> > > other quirk system.
> > >
> > > So kexec-tools can switch to use old way if kernel use ioremap.
This sounds like a good approach to use, but I think we should still
have a way to force it to use the old way if necessary (can't think of a
use case for that off the top of my head, but I'm sure someone can :)
I think a sort of hybrid approach between detecting the mapping scheme,
and having a command-line option would probably be best:
- Detect which mapping method we used.
- Default to noefi if the old mapping method was used, default to
efi if new mapping was used.
- Allow users to specify either --efi or --noefi when kexec'ing to
override the suggested default, determined above.
Make sense? We alway seems to run into trouble when we try to make
decisions on the user's behalf, and not allow them to have the final
say.
> > > Adding Matt and Boris to cc, to see if they have idea.
> > > Thanks
> > > Dave
> > >
> > > ----- Original Message -----
> > > From: "Vivek Goyal" <vgoyal at redhat.com>
> > > To: "Dave Young" <dyoung at redhat.com>
> > > Cc: horms at verge.net.au, kexec at lists.infradead.org
> > > Sent: Friday, May 23, 2014 9:28:34 PM
> > > Subject: Re: [PATCH] x86: do not enable efi boot for sgi uv machine
> > >
> > > On Fri, May 23, 2014 at 06:14:55PM +0800, Dave Young wrote:
> > > >
> > > > kexec/kdump uefi support depends on the 1:1 mapping scheme
> > > > in 3.14 kernel but SGI reported that 1:1 mapping does not work on
> > > > their UV system. thus there's below commit to switch back to
> > > > old ioremap way for sgi uv machines.
> > > >
> > > > So for kexec-tools before we got the 1:1 mapping support on those
> > > > machines we should also use old way that means boot 2nd kernel
> > > > without uefi.
>
> Yes, the old workaround to allow the kdump kernel to boot was
> to add the noefi bootline option, which also meant passing all
> the memory ranges as kernel boot line options (since noefi meant
> no EFI memory map info). An ugly situation. That is why we
> want to get Boris' mapping changes working on SGI UV, so that
> kexec/kdump work without ugly workarounds.
>
>
> > Well, we did find the bug in a combined debug session and SGI will be
> > issuing a fix soon. I don't know whether any quirk will be needed for
> > systems which don't have the fix - I guess that's something for SGI
> > people to decide. CCed and leaving in the rest for reference.
> >
> > @Alex, Russ: this is about using kexec on UEFI boxes.
>
> Thanks for the heads up. Our bios made an assumption about
> mapping that was valid with the old mapping scheme but not
> with the new. Fortunately the fix will work with both old
> and new kernels, so the fix can be added in the next bios
> update. But we still have to be careful when removing the
> quirk, to avoid someone trying a new kernel with old bios
> and not being able to boot.
>
>
> > > > Tested on a uv1 machine.
> > > >
> > > > Here is the kernel commit to quirk out SGI UV:
> > > > commit a5d90c923bcfb9632d998ed06e9569216ad695f3
> > > > Author: Borislav Petkov <bp at suse.de>
> > > > Date: Tue Mar 4 17:02:17 2014 +0100
> > > >
> > > > x86/efi: Quirk out SGI UV
> > > >
> > > > Alex reported hitting the following BUG after the EFI 1:1 virtual
> > > > mapping work was merged,
> > > >
> > > > kernel BUG at arch/x86/mm/init_64.c:351!
> > > > invalid opcode: 0000 [#1] SMP
> > > > Call Trace:
> > > > [<ffffffff818aa71d>] init_extra_mapping_uc+0x13/0x15
> > > > [<ffffffff818a5e20>] uv_system_init+0x22b/0x124b
> > > > [<ffffffff8108b886>] ? clockevents_register_device+0x138/0x13d
> > > > [<ffffffff81028dbb>] ? setup_APIC_timer+0xc5/0xc7
> > > > [<ffffffff8108b620>] ? clockevent_delta2ns+0xb/0xd
> > > > [<ffffffff818a3a92>] ? setup_boot_APIC_clock+0x4a8/0x4b7
> > > > [<ffffffff8153d955>] ? printk+0x72/0x74
> > > > [<ffffffff818a1757>] native_smp_prepare_cpus+0x389/0x3d6
> > > > [<ffffffff818957bc>] kernel_init_freeable+0xb7/0x1fb
> > > > [<ffffffff81535530>] ? rest_init+0x74/0x74
> > > > [<ffffffff81535539>] kernel_init+0x9/0xff
> > > > [<ffffffff81541dfc>] ret_from_fork+0x7c/0xb0
> > > > [<ffffffff81535530>] ? rest_init+0x74/0x74
> > > >
> > > > Getting this thing to work with the new mapping scheme would need more
> > > > work, so automatically switch to the old memmap layout for SGI UV.
> > > >
> > > >
> > > > Signed-off-by: Dave Young <dyoung at redhat.com>
> > > > ---
> > > > kexec/arch/i386/x86-linux-setup.c | 15 ++++++++++++++-
> > > > 1 file changed, 14 insertions(+), 1 deletion(-)
> > > >
> > > > --- kexec-tools.orig/kexec/arch/i386/x86-linux-setup.c
> > > > +++ kexec-tools/kexec/arch/i386/x86-linux-setup.c
> > > > @@ -817,12 +817,25 @@ out:
> > > > return;
> > > > }
> > > >
> > > > +static int is_sgi_uv_machine(void)
> > > > +{
> > > > + DIR *sgi_dir;
> > > > +
> > > > + sgi_dir = opendir("/sys/firmware/sgi_uv");
> > > > + if (sgi_dir) {
> > > > + closedir(sgi_dir);
> > > > + return 1;
> > > > + }
> > > > +
> > > > + return 0;
> > > > +}
> > > > +
> > > > void setup_linux_system_parameters(struct kexec_info *info,
> > > > struct x86_linux_param_header *real_mode)
> > > > {
> > > > /* get subarch from running kernel */
> > > > setup_subarch(real_mode);
> > > > - if (bzImage_support_efi_boot)
> > > > + if (bzImage_support_efi_boot && !is_sgi_uv_machine())
> > > > setup_efi_info(info, real_mode);
> > >
> > > Hi Dave,
> > >
> > > I think instead of always falling back to old "noefi" method for SGI UV
> > > machines, we should probably provide a config option to override default
> > > behavior. Something like "--nouefi". And let user/distributions decide
> > > in what cases to use that parameter.
> > > Reason being, that at some point of time this limitation will be fixed.
> > > And at that point of time if we modify kexec-tools, then it will stop
> > > working with older kernels. And then same issue will arise that
> > > kexec-tools is not working with older kernels.
> > >
> > > If we just provide a way to override default, then distributions in their
> > > scripts should know what kernels work what way and automatically use or
> > > not use option accordingly.
> > >
> > > Thanks
> > > Vivek
> > >
> > > _______________________________________________
> > > kexec mailing list
> > > kexec at lists.infradead.org
> > > http://lists.infradead.org/mailman/listinfo/kexec
> >
> > --
> > Regards/Gruss,
> > Boris.
> >
> > Sent from a fat crate under my desk. Formatting is fine.
> > --
>
> --
> Russ Anderson, Kernel and Performance Software Team Manager
> SGI - Silicon Graphics Inc rja at sgi.com
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