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Date: Fri, 25 Feb 2022 23:48:41 -0500 From: Samuel Bronson <naesten@...il.com> To: linux-kernel@...r.kernel.org Cc: linux-riscv@...ts.infradead.org Subject: Re: [PATCH v3 1/8] riscv: Avoid unaligned access when relocating modules Emil Renner Berthing <kernel@...il.dk> writes: > With the C-extension regular 32bit instructions are not > necessarily aligned on 4-byte boundaries. RISC-V instructions > are in fact an ordered list of 16bit native-endian > "parcels", so access the instruction as such. Hold on a minute, this is what it says in my copy of the Unprivileged ISA: ,---- | RISC-V base ISAs have either little-endian or big-endian memory systems, | with the privileged architecture further defining bi-endian operation. | Instructions are stored in memory as a sequence of 16-bit *little-endian* | parcels, regardless of memory system endianness. Parcels forming one | instruction are stored at increasing halfword addresses, with the | *lowest-addressed parcel holding the lowest-numbered bits* in the | instruction specification. `---- [Emphasis mine.] In other words, the parcels are little endian, and they're arranged in little-endian order. System endianness doesn't matter, it collapses to plain old little-endian. (I'm really not sure why they describe the ordering in such a round-about way; I assume that's the source of the confusion here?)
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