Given how long it took to come to a conclusion of the discussions around
https://github.com/systemd/systemd/issues/35026, let's add a comment
that makes this easier to grok for the next time this comes up.
Follow-up for: 6e207b370e
Outside of x86, some machines (e.g. Apple silicon, AMD Opteron A1100)
have physical memory mapped above 4GiB, meaning this allocation will
fail, causing the entire boot process to fail on these machines.
This commit makes it so that the below-4GB address space allocation
requirement is only set on x86 platforms, and not on other platforms
(that don't have the specific Linux x86 boot protocol), thereby fixing
boot on those that have no memory mapped below 4GiB in their address
space.
Tested on an Apple silicon M1 laptop and an AMD x86_64 desktop tower.
Fixes: #35026
I very much dislike the approach in which we were mixing Linux and UEFI C code
in the same subdirectory. No code was shared between two environments. This
layout was created in e7dd673d1e, with the
justification of "being more consistent with the rest of systemd", but I don't
see how it's supposed to be so.
Originally, when the C code was just a single bootctl.c file, this wasn't so
bad. But over time the userspace code grew quite a bit. With the moves done in
previuos commits, the intermediate subdirectory is now empty except for the
efi/ subdir, and this additional subdirectory level doesn't have a good
justification. The components is called "systemd-boot", not "systemd-efi", and
we can remove one level of indentation.
Lennart Poettering
Yu Watanabe
anonymix007
andre4ik3
Zbigniew Jędrzejewski-Szmek