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eBPF Standard Documentation
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ISA: Incomplete text about MOVSX #69

Closed dthaler closed 4 months ago

dthaler commented 5 months ago

Yonghong Song yonghong.song@linux.dev wrote:

(Resending since a spam filter seems to have blocked the first attempt.)

Is there any semantic difference between the following two instructions?

{.opcode = BPF_ALU64 | BPF_MOV | BPF_K, .offset = 0, .imm = -1}

This is supported. Sign extension of -1 will be put into ALU64 reg.

{.opcode = BPF_ALU64 | BPF_MOVSX | BPF_K, .offset = 32, .imm = -1}

This is not supported. BPF_MOVSX only supports register extension. We should make it clear in the doc.

dthaler commented 5 months ago

Fixed in https://mailarchive.ietf.org/arch/msg/bpf/WNFgh9ynOFnFGuakBkO4TCNrXDc/

dthaler commented 4 months ago

Fixed in draft -01