Re: [PATCH v6 9/9] x86: Pass memory range via E820 for kdump

Simon Horman
2014-04-21T00:01:41Z

On Thu, Apr 17, 2014 at 01:58:17PM +0800, Dave Young wrote:
> On 04/17/14 at 01:48pm, WANG Chao wrote:
> > On 04/17/14 at 01:29pm, Dave Young wrote:
> > > On 04/14/14 at 10:55pm, WANG Chao wrote:
> > > > command line size is restricted by kernel, sometimes memmap=exactmap has
> > > > too many memory ranges to pass to cmdline. And also memmap=exactmap and
> > > > kASLR doesn't work together.
> > > >
> > > > A better approach, to pass the memory ranges for crash kernel to boot
> > > > into, is filling the memory ranges into E820.
> > > >
> > > > boot_params only got 128 slots for E820 map to fit in, when the number of
> > > > memory map exceeds 128, use setup_data to pass the rest as extended E820
> > > > memory map.
> > > >
> > > > kexec boot could also benefit from setup_data in case E820 memory map
> > > > exceeds 128.
> > > >
> > > > Now this new approach becomes default instead of memmap=exactmap.
> > > > saved_max_pfn users can specify --pass-memmap-cmdline to use the
> > > > exactmap approach.
> > > >
> > > > Signed-off-by: WANG Chao <chaowang@redhat.com>
> > > > Tested-by: Linn Crosetto <linn@hp.com>
> > > > Reviewed-by: Linn Crosetto <linn@hp.com>
> > > > ---
> > > > kexec/arch/i386/crashdump-x86.c | 6 +-
> > > > kexec/arch/i386/x86-linux-setup.c | 149 +++++++++++++++++++++++++-------------
> > > > kexec/arch/i386/x86-linux-setup.h | 1 +
> > > > 3 files changed, 103 insertions(+), 53 deletions(-)
> > > >
> > > > diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
> > > > index 7b618a6..4a1491b 100644
> > > > --- a/kexec/arch/i386/crashdump-x86.c
> > > > +++ b/kexec/arch/i386/crashdump-x86.c
> > > > @@ -979,7 +979,8 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
> > > > dbgprintf("Created elf header segment at 0x%lx\n", elfcorehdr);
> > > > if (delete_memmap(memmap_p, &nr_memmap, elfcorehdr, memsz) < 0)
> > > > return -1;
> > > > - cmdline_add_memmap(mod_cmdline, memmap_p);
> > > > + if (arch_options.pass_memmap_cmdline)
> > > > + cmdline_add_memmap(mod_cmdline, memmap_p);
> > > > if (!bzImage_support_efi_boot)
> > > > cmdline_add_efi(mod_cmdline);
> > > > cmdline_add_elfcorehdr(mod_cmdline, elfcorehdr);
> > > > @@ -995,7 +996,8 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
> > > > type = mem_range[i].type;
> > > > size = end - start + 1;
> > > > add_memmap(memmap_p, &nr_memmap, start, size, type);
> > > > - cmdline_add_memmap_acpi(mod_cmdline, start, end);
> > > > + if (arch_options.pass_memmap_cmdline)
> > > > + cmdline_add_memmap_acpi(mod_cmdline, start, end);
> > >
> > > Seems memmap_p contains the acpi ranges as well, so cmdline_add_memmap_acpi is
> > > not necessary anymore, just improve cmdline_add_memmap to add both RAM and ACPI
> > > ranges is enough.
> >
> > I can do that. But is it what the patchset is really about ...
> >
> > I'm not keen about doing too much cleanup in this series now since it's
> > already v6. I really want to get this in as early as possible to
> > cope with calgary iommu change in the kernel.
> >
> > I prefer to first get this patch in if there's no problem in it and then
> > look back and think about how we can clean up the code block which have
> > been there for historical reason.
>
> I think the cleanup is worth, but if you want to do it later I'm fine.
> So should better leave the patch 5/9 to later cleanup as well.
>
> Thus except for 5/9, for other patches:
> Acked-by: Dave Young <dyoung@redhat.com>

This sounds fine to me.

Chao, would you care to re-post the series without 5/9 ?