ARM プロセッサでの asmlinkage の意味

Russell King さんが次のように書いてます。

ARM doesn't require any special API modification to call functions
from assembly.

x86 has two different calling conventions - one is to stack all function
arguments, the other passes some arguments via registers.  asmlinkage
selects between them.

However, we keep the asmlinkage labelling on ARM because it's useful to
indicate which functions are called by assembly - and therefore which
need closer inspection when their signature is changed to make sure the
assembly calling them is also fixed.

http://lists.infradead.org/pipermail/linux-arm-kernel/2010-May/014882.html

要は x86 で意味を持つけど ARM では意味を持たないと。ラベルの意味があるのでそのままにしている。