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loongarch: hostreqs: stop abusing the "old/new-world" concepts

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It's now 2026 and it unfortunately turns out the "old-world" and
"new-world" concepts have become overloaded too much.  In many contexts
they are even abused for well-known platform-independant ABI issues like
 SONAME differences.

As an educational project, let's get ourselves out of this mess.
This commit is contained in:
Xi Ruoyao
2026-05-09 00:54:11 +08:00
parent 9713f2fc5f
commit d4a6dfcdca
1 changed files with 58 additions and 13 deletions
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71
chapter02/hostreqs.xml
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@@ -110,24 +110,69 @@
LoongArch.</para>
<important>
<!-- We deliberately hard-code 5.19 instead of using min-kernel
here, for the correctness even after we raise min-kernel to
6.1 - I'm not so optimistic to believe old-world will have
its natural death before Dec. 2027, when the LFS trunk will
eventually raise min-kernel to 6.1 and we'll merge. -->
<para>
If a Linux distribution on LoongArch provides a kernel older than
&min-kernel;, it indicates the distribution is using a preliminary
version of the kernel ABI. The preliminary draft was rejected by
the kernel maintainers and it's fundamentally incompatible with
the packages we will built for LFS. Such <quote>old-world</quote>
distributions (for example, Loongnix) cannot be used as a host
distro for building LFS.
If a Linux distribution on LoongArch provides a kernel older
(exclusively) than 5.19, it indicates the distribution is using a
preliminary draft of the ABI provided by the kernel for the
userspace. The ABI had been revised for several times before it
was finally integrated into Linux 5.19 and stablized, so those old
kernel versions are incompatible with some critical packages those
we will build (at least, glibc and GCC). Such an
<quote>old-world</quote> distro (for example, Loongnix 20) cannot
be used as a host distro for building LFS.
</para>
<para>
Do not attempt to update the kernel to &min-kernel; or later on
a old-world distro because doing so will cause a boot failure.
Use a <quote>new-world</quote> distribution providing Linux Kernel
&min-kernel; or newer instead. You may need to contact the vendor
of your hardware to get a firmware update for booting a new-world
distribution because the boot protocol of LoongArch is stabilized
after the launch of the early LoongArch hardwares.
an old-world distro because doing so will almost definitely cause
a boot failure due to the ABI difference (i.e. the
<command>init</command> process will likely crash very soon after
startup). Use a <quote>new-world</quote> distro providing Linux
5.19 or newer instead. <!-- If the kernel version of a
<quote>new-world</quote> distro is older than &min-kernel;, you
may upgrade the kernel on your own. (uncomment when we raise
min-kernel to 6.1) -->
</para>
<para>
Another source of the compatability issues is the boot protocol
provided by the firmware. The UEFI specification for LoongArch
had been also revised for several times, similar to the revisions
of the kernel ABI for userspace. The GRUB and Linux kernel
packages those we'll build for LFS are not compatible with the
old firmware developed following the early drafts of the UEFI
specifications. Those old firmware implementations are only
reported to exist on the earliest models of the LoongArch hardware
based on Loongson 3A5000 processors and Loongson 7A1000 bridge
chips. If you have such a board, you may need to contact the
vendor of your hardware to get a firmware update in order to boot
LFS.
</para>
<para>
Some sources describe the boot protocol difference as a part of
the <quote>old-world</quote> with <quote>new-world</quote>
difference. We consider such a description misleading and
confusing. In fact, the boot protocol difference is orthogonal
with the difference of the kernel ABI for userspace. You may boot
some <quote>new-world</quote> distros (for example, AOSC OS) on
a firmware implementation providing the old boot protocol because
the maintainers of those distros have custom modifications to the
GRUB and Linux kernel for the old boot protocol support and build
LFS fine, but then LFS will fail to boot there. Similarly, many
<quote>old-world</quote> distros can also boot on newer firmware
implementations following the stabilized UEFI specification. As
the result, clearly distinguishing those two kinds of differences
is important to avoid confusions like <quote>my board has a [so
called] new-world firmware and I've booted a distro
[actually, old-world, perhaps just Loongnix 20] there fine, so the
distro must be new-world but why does it fail to work as a host
distro for building LFS?</quote>
</para>
</important>