|Subject:||GRUB rebuild without -fno-PIC and -fno-pie / -fno-PIE options for ARM 64 (Qualcomm EFI)|
|Date:||Sun, 30 Dec 2018 16:34:24 +0100|
|User-agent:||Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0|
I feel sorry to mail everyone and I hope this won't disturb too
much people. But I'm stuck and I'm pretty sure your help will be
First I would like to give all the information :
I have a laptop computer (Asus Novago, TP370QL) running on an
ARM64 platform (Qualcomm Snapragon 835), with UEFI support, Secure
Boot disabled, and "Boot USB First" enabled. It's a laptop shaped
smart-phone that has the same features that a standard x86_64-efi
It's delivered with Windows 10 Pro on it, installed in the exact
same way that on a x86_64-efi computer (same partitions scheme,
ESP, recovery, same files etc... just it's aarch64 built instead
I have a working USB re-installation media (that can be booted
trough EFI) and I already successfully cleared the entire disk
(like dd if=/dev/zero of=/dev/sda but with Windows "diskpart" and
"clean" commands). And of course the re-installation media is
working - if not I would have been really disappointed ;)
I'm also able to boot EFI files on it, I just have to ensure the USB disk (or SD card) has GPT partitionning, at least 1 partition that is ESP type, and FAT32 formatted, containing a "/efi/boot/bootaa64.efi" file that the computer will execute at startup.
Is some of you are interested in seeing what it looks like : http://image.noelshack.com/fichiers/2018/52/6/1546083005-infact.png
My problem :
GRUB doesn't work (it freezes on the "Asus" logo and I have to
force shutdown the computer by pressing the power button 5
seconds). Same problem for GRUB versions used in Debian, Ubuntu,
even Buster and 18.10 versions (using 4.18 kernel, where all the
Qualcomm things are now mainlined).
And by seeing what are the gcc used options for GRUB, and
comparing those options with the ones that are used for the
working "UEFI-SIMPLE" (https://github.com/pbatard/uefi-simple),
I found that the -fno-PIE, -fno-pie, and -fno-pic and -fno-PIC
options shouldn't be used ! The default compiler behavior is the
right one (-fPIC and -fPIE are enabled by default) but grub
Makefiles are disabling it. And it does not work on this computer
when disabled. If one of the "-fno-PIE -fno-pie -fno-pic -fno-PIC"
are used, the computer won't be able to start the resulting
UEFI-SIMPLE efi file.
The "-no-pie" option, however, isn't causing any problem (and can
be used in parallel of -fPIC and -fPIE option, even if it sound
pretty strange : the resulting UEFI-SIMPLE efi file is still
working that way). As I understand, those options are dealing with
Global Offset Tables (GOT) with more information here : https://en.wikipedia.org/wiki/Position-independent_code
What I did and where I'm stuck :
I'm trying to create a GRUB efi file that my ARM64 computer will
be able to execute, even if the first result is a working error
message ! I would then be happy because I will then manage to
reconfigure things in order to make the debian installer to start
with this grub file. Having grub to work on this computer is my
quest, today. In order to test what should happen when it will be
working, I already did that on a x86_64-efi computer (and I got an
error message and a grub-rescue line but that's fine).
I downloaded the grub source code here : ftp://ftp.gnu.org/gnu/grub/grub-2.02.tar.gz
And I found an ARM64 computer already working on Linux (Debian 9)
on "Scaleway" provider, in order to build things in an easy way.
By running ./configure command, then make -j 4, and by playing
with grub-install, it's giving an EFI file that my arm64 computer
won't boot (freeze). So I tried to modify the "configure" file by
commenting lines 26055, 26056, 26057, then 26116, 26117.
Disabling those options are making, by default, the -fPIE and -fPIC flags active. This is not compatible with the mcmodel=large flag, so I disabled it too, in conf/Makefile.common : 17, 18, 19
However, disabling only the -mcmodel=large flag, with no other modification, is already giving an error at the end of the build process, when trying to transform the xxx.module files into xxx.mod files.
Removing the -fno-PIC, -fno-PIE and -fno-pie flags then leads to
a different error, at the end too.
Enabling the -fpic and -fpie flags (lower case) is leading to another error :
I also tried to remove the -no-pie flag but it makes another flag
(-Wl,-r) incompatible. When I removed the -r flag to the linker, I
got sooner build errors when trying to create *.module files from
So here I'm stuck ! Despite the days I spent on this, I'm definitely not able to deal with those flags as finely as you, developers, seemed to enable it or disable it in different portions of the grub's code.
Can someone help me in this quest of having grub working on those
Qualcomm ARM64 laptops ? I think the initial mission is to
re-enable the -fPIC and -fPIE flags but it's like this missions
implies others missions to succeed.
Thank you (very) much in advance for your help !
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