Re: [RFC][PATCH 21/22] Add Makerules to build %.o and %.os from %.i8

[Gary Benson <gbenson at redhat dot com>]

Joseph Myers wrote:
> On Tue, 20 Oct 2015, Gary Benson wrote:
> > This commit adds make rules to build %.o and %.os files from %.i8
> > Infinity note source code.
> > 
> > In order to ensure the correct preprocessor and assembler are used
> > for cross-builds the compilation is done in three stages.  The target
> > preprocessor specified at ./configure time is used to preprocess the
> > %.i8 source; I8C consumes this preprocessed source and emits assembly
> > language; and finally the target assembler specified at ./configure
> > time is used to assemble the generated assembly language into object
> > code.
> > 
> > I don't *think* the %.o and %.os files should differ (they don't
> > contain "real" code, just PT_NOTE sections) but please tell me if
> > I'm wrong and I will add a separate %.S -> %.os rule.
> 
> On some platforms the options passed to GCC when compiling a .S file
> affect the options passed to the assembler, which in turn affects
> the ELF header (this applies e.g. to MIPS passing -KPIC).  So I
> think you do need to compile the files separately.

Ok, I will change this.

> On some platforms, even assembler files with no actual code need to
> contain certain assembler directives to be ABI-compatible with those
> generated by the compiler.  In particular, this applies to ARM; see
> the .eabi_attribute directives in sysdeps/arm/sysdep.h.  If
> generating a .S file, you should make sure it includes <sysdep.h> so
> that such directives are present.

I did not know that.  Is this because all glibc files include this
file with the directives?

(I guess what I'm asking is, in general, if I have a .c file and a
.S file with no special directives, can I compile and link them and
expect it to work?)

For glibc is it ok if I add '-include sysdep.h' to the %.S -> %.o*
rules?

Thanks,
Gary

-- 
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