Re: [edk2-devel] How /sys/firmware/fdt getting created

["Leif Lindholm" <leif.lindholm@linaro.org>]

On Thu, Oct 31, 2019 at 11:07:52AM +0100, Laszlo Ersek wrote:
> +Leif, comment at bottom

Thanks Laszlo. +Dann, -kexec.

> On 10/30/19 09:16, Prabhakar Kushwaha wrote:
> >> So if you want to add these properties, you should add them there.
> >>
> >> Can you explain why doing this is necessary?
> > 
> > I am trying to test kexec -p (kdump feature) on CentOS-release
> > 7.7.1908 and Ubuntu-18.04 distributions.
> > 
> >  "kexec -p" command show error on Ubuntu. While no error on CentOS
> > 
> > CentOS:
> > $ kexec -p /boot/vmlinuz-`uname -r` --initrd=/boot/initramfs-`uname
> > -r`.img --reuse-cmdline
> > $    ==> No error
> > 
> > Ubuntu
> > $ kexec -p /boot/vmlinuz-`uname -r` --initrd=/boot/initrd.img-`uname
> > -r` --reuse-cmdline
> > $ kexec: elfcorehdr doesn't fit cells-size.
> > $ kexec: setup_2nd_dtb failed.
> > $ kexec: load failed.
> > $ Cannot load /boot/vmlinuz-5.4.0-rc4+
> > 
> > Note: Both CentOS and Ubuntu has Linux-5.4-rc4 tag.
> > 
> > When i debugged further reason for Ubuntu error is due to
> > address-cells and size-cells as "1"
> > log from kexec tool :-
> > load_crashdump_segments: elfcorehdr 0x7f7cbfc000-0x7f7cbff7ff
> > read_1st_dtb: found name =dtb_sys  /sys/firmware/fdt
> > get_cells_size: #address-cells:1 #size-cells:1
> > 
> > On CentOS both values are "2".
> > log from kexec tool :-
> > load_crashdump_segments: elfcorehdr 0xbf98bf0000-0xbf98bf33ff
> > read_1st_dtb: found nmae=dtb_sys /sys/firmware/fdt
> > get_cells_size: #address-cells:2 #size-cells:2
> > 
> > Note: Kexec tool read values from /sys/firmware/fdt.
> > 
> > I am trying to figure out why 2 distributions showing different values.
> 
> http://git.savannah.gnu.org/cgit/grub.git/commit/?id=347210a5d5ce655b95315f320faa515afb723c11
> 
> Ubuntu probably ships a grub version that lacks this commit.

Yes, it came after the 18.04 release.
Dann: given that 18.04 is LTS, would it be reasonable to cherry-pick
this grub patch? I would consider the behaviour without it to be a
bug.

/
    Leif

> (The commit was first released as part of upstream grub-2.04. I have no
> idea what version of grub is shipped in the CentOS distro you mention
> above -- it could be based upon upstream 2.04, or the upstream patch may
> have been backported to CentOS.)
> 
> Thanks
> Laszlo
>