Thread (63 messages) 63 messages, 10 authors, 2025-03-27

Re: [RFC PATCH V3 00/43] rv64ilp32_abi: Build CONFIG_64BIT kernel-self with ILP32 ABI

From: Liam R. Howlett <hidden>
Date: 2025-03-25 19:24:54
Also in: bpf, kvm, kvm-riscv, linux-arch, linux-btrfs, linux-crypto, linux-fsdevel, linux-input, linux-media, linux-mm, linux-nfs, linux-perf-users, linux-riscv, linux-sctp, linux-serial, linux-trace-kernel, linux-usb, lkml, netfilter-devel

* David Hildenbrand [off-list ref] [250325 14:52]:
On 25.03.25 13:26, Peter Zijlstra wrote:
quoted
On Tue, Mar 25, 2025 at 08:15:41AM -0400, guoren@kernel.org wrote:
quoted
From: "Guo Ren (Alibaba DAMO Academy)" <guoren@kernel.org>

Since 2001, the CONFIG_64BIT kernel has been built with the LP64 ABI,
but this patchset allows the CONFIG_64BIT kernel to use an ILP32 ABI
I'm thinking you're going to be finding a metric ton of assumptions
about 'unsigned long' being 64bit when 64BIT=y throughout the kernel.

I know of a couple of places where 64BIT will result in different math
such that a 32bit 'unsigned long' will trivially overflow.

Please, don't do this. This adds a significant maintenance burden on all
of us.
Fully agreed.
I would go further and say I do not want this to go in.

The open ended maintenance burden is not worth extending hardware life
of a board with 16mb of ram (If I understand your 2023 LPC slides
correctly).

Thank you,
Liam
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