On 6/3/22 17:32, Xi Ruoyao wrote:
On Thu, 2022-06-02 at 22:09 +0800, WANG Xuerui wrote:
For this, I don't know if Huacai should really just leave those
modification in the downstream fork to keep the upstream Linux clean of
such hacks, because to some degree dealing with such notoriety is life,
it seems to me. I think at this point Huacai would cooperate and tweak
the patch to get rid of the SVAM and other nonstandard bits as much as
possible, and I'll help him where necessary too.
To me any new firmware for PC-like platforms should implement UEFI. For
embedded platforms device tree support will be added later.
For those guys impossible or unwilling to upgrade the firmware, it may
be possible to implement a compatibility layer and the booting procedure
will be like:
old firmware -> bootloongarch.efi -> customized u-boot -> bootloongarch64.efi (grub) -> efi stub (kernel)
--------- compatibility layer -------- ^^^^^^^^ normal UEFI compatible stuff ^^^^^^^^^
new firmware -> bootloongarch64.efi (grub) -> efi stub (kernel)
The old firmware route would be similar to the booting procedure of
Asahi Linux. I think this can be implemented because it's already
implemented on M1 even while Apple is almost completely uncooperative.
This is a bit off-topic (we're basically hurrying up to get the port
into v5.19-rc1 and discussing ways to achieve that), but yeah
definitely. I've had the same idea right after knowing the LoongArch
firmware would also have "new-world" variant, then I contacted some
firmware engineers working on LoongArch boards, I think they agreed on
the approach overall.
However, making the kernel itself capable of booting on both BPI and
new-world UEFI firmware flavors may have its merits after all; one
scenario I could come up with is that user reboots and upgrades their
firmware, *before* updating their old-world kernel, and bang! system
soft-bricked. All such cases involve old-world distros that already
deviate a little bit from vanilla upstream code, so such BPI support
needn't be mainlined for avoiding this scenario.
Just my 2 cents. I know almost nothing about booting.
That's fine, we all know nothing in the beginning ;-)
