Messages in this thread | | | Date | Mon, 13 Oct 2008 15:34:09 +0100 | From | Alan Swanson <> | Subject | Binutils bug on not using NOPL with i686 needs persuasive arguments |
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Hi. (Usual not subscribed CC request.)
I need some heavyweight assistance with verifying and convincing the binutils gas maintainer that using NOPL on i686 is undesirable and also fixing it so that only march changes the NOP sequence used and not mtune.
This was from from thread "[BUG] x86 kenel won't boot under Virtual PC" where NOPL was deemed rather bad and a bug requested. I was investigating a Geode miniitx motherboard and it was still an issue with no bug was raised so did so.
http://marc.info/?l=linux-kernel&m=122090041613423&w=2 http://sourceware.org/bugzilla/show_bug.cgi?id=6957
MARCH VERSUS MTUNE The bug was closed as works for me but the patch that was applied doesn't seem to change anything in regards mtune versus march selection, though the testcase result is correct. However I'm worried it now means passing -march=i686 will start using NOPL and break things that were conviently missed by gcc stripping the mtune option passed to gas. Which leads to...
NO NOPL WITH I686 Though pretty unlikely and just being standards strict, as an Intel employee there may be a possible self-interest and makes it harder convincing him that that NOPL is undesirable with -march=i686 even if an original standard. From comment 10 I don't see how using f32_patt will prevent the assembler taking SSE instructions by default but I don't have the knowledge to argue that point.
-- Thanks, Alan.
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