On Tue, 2013-08-27 at 11:49 +0100, Catalin Marinas wrote: > On Fri, Aug 23, 2013 at 04:16:42PM +0100, Mark Salter wrote: > > The current vmlinux.lds.S places the notes sections between the > > end of rw data and start of bss. This means that _edata doesn't > > really point to the end of data. Since notes are read-only, this > > patch moves them to the read-only segment so that _edata does > > point to the end of initialized rw data. > > > > Signed-off-by: Mark Salter <msal...@redhat.com> > > --- > > arch/arm64/kernel/vmlinux.lds.S | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > diff --git a/arch/arm64/kernel/vmlinux.lds.S > > b/arch/arm64/kernel/vmlinux.lds.S > > index f5e5574..f8ab9d8 100644 > > --- a/arch/arm64/kernel/vmlinux.lds.S > > +++ b/arch/arm64/kernel/vmlinux.lds.S > > @@ -71,6 +71,7 @@ SECTIONS > > > > RO_DATA(PAGE_SIZE) > > EXCEPTION_TABLE(8) > > + NOTES > > _etext = .; /* End of text and rodata section */ > > > > . = ALIGN(PAGE_SIZE); > > @@ -122,8 +123,6 @@ SECTIONS > > } > > _edata_loc = __data_loc + SIZEOF(.data); > > > > - NOTES > > - > > BSS_SECTION(0, 0, 0) > > _end = .; > > The _edata is set before NOTES, so I don't fully understand where the > problem is. > The problem *is* _edata before the NOTES. We need a symbol to mark the end of initialized data. This should be _edata but _edata doesn't currently account for NOTES. In the EFI stub I'm working on, the PE/COFF header needs to know the end of the image. If we use _edata, we wouldn't include NOTES, so we're left with __bss_start. But _bss_start may not be exactly right because of alignment rounding and it is ugly to use for that purpose. So we either need a new symbol following NOTES, or move _edata past NOTES, or move NOTES. I chose the latter because NOTES are readonly and don't really need to be part of the RW segment.
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