Messages in this thread | | | Subject | Re: [PATCH] x86: clean up vdso-layout.lds.S | From | Petr Tesarik <> | Date | Tue, 09 Jun 2009 09:57:37 +0200 |
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Roland McGrath píše v Út 09. 06. 2009 v 00:52 -0700: > > > I am wondering why we need -P -C here - but we do not need it for lds.S files? > > > Seems like something we could let go. > > AFAIK these only affect readability of the lds.s output files. > The difference should be entirely cosmetic. > > > > > > .altinstructions : { *(.altinstructions) } > > > > > @@ -43,9 +42,49 @@ SECTIONS > > > > > */ > > > > > . = ALIGN(0x100); > > > > > > What is 0x100? > > > > Um. No idea. Roland, you added this line in commit > > f6b46ebf904f69a73907a5e6b1ed2228e3f03d9e. Can you shed some light on > > this magic constant? > > You mean this one: > > /* > * Align the actual code well away from the non-instruction data. > * This is the best thing for the I-cache. > */ > . = ALIGN(0x100); > > Reading the comment might make it obvious that it's intended for optimal > code alignment. I suspect someone at the time told me 256 is as big as an > I-cache line was ever likely to get. You could use L1_CACHE_BYTES instead > I suppose. > > > What would you expect? The linker script language is quite limited in > > its capabilities... Best I could do is split the ".broken" section into > > several sections and move the descriptions from the individual comments > > above here. If this muckle of empty ".broken.*" sections gets correctly > > discarded and triggers no bug in binutils, I can probably do it. > > Adding more sections and section names unnecessarily bloats the size of the > vDSO image. Keep the set of output sections to the necessary minimum.
Which version of binutils are you using? I'm using binutils-2.19, and all empty sections get completely discarded, i.e. they do not affect the size of the output in any way.
Petr Tesarik
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