[U-Boot] [PATCH 1/3] common: Add symbol handling for generic lists into Makefile

[Marek Vasut]

Dear Joe Hershberger,

> Hi Marek,
[...]

It's a RFC, lemme explain:

> > -$(obj)u-boot-spl.lds: $(LDSCRIPT) depend
> > +$(obj)u-boot-spl.lst: $(LIBS)
> > +       $(OBJDUMP) -h $(LIBS) | \

Dump the section headers in all object files

> > +       sed -n -e 's/.*\(\.u_boot_list[^ ]\+\).*$$/\1/p' | \

Filter only \.u_boot_list.* symbols

> > +       sed 's/\.[^\.]\+$$//' | \

Remove the last .[^.]$ from each line. That's because the last part behind . is 
the name of the variable, we don't need that for generation of subsection 
boundary symbols.

> > +       sed -n ':s /^.\+$$/ { p;s/^\(.*\)\.[^\.]*$$/\1/;b s }' | \

For each line in format .u_boot_list.x.y.z, generate a list of as such (list of 
substrings with . as separator):
.u_boot_list.x.y.z
.u_boot_list.x.y
.u_boot_list.x
.u_boot_list

> > +       sed -n 's/\./.#/g;h;s/$$/\a/p;g;s/$$/@/p;g;s/$$/~/p;' | \

For each line, print the line thrice, first time append \a at the end, second @ 
and third ~. Also replace each dot with .# . See [1] and look for the list under 
"The order_end Keyword" section.

> > +       LC_COLLATE=C sort -u | \

Sort the list, it's imperative to use the C collating here, because of [1]. This 
results in lines ending with \a float above all lines ending with either @ or 
continuing with further dots. Same goes for ~, which falls at the end.

> > +       sed 's/#//g' | \

Remove the hashes.

> > +       sed -n -e '/\a$$/ { s/\./_/g;s/\a$$/__start = .;/p; }'\
> > +               -e '/~$$/ { s/\./_/g;s/~$$/__end = .;/p; }'\
> > +               -e '/@$$/ { s/\(.*\)@$$/*(SORT(\1.*));/p }' >$@

Replace \a with __start ... so this defines the subsection start marker, ~ with 
__end for subsection end marker and lines ending with @ with the 
SORT(subsection.*) so they catch the contents of subsection.

> Could you not reuse this complicated logic by defining a make function
> and then call + eval it?  Something like this:


Can you elaborate more? I don't quite get it ... :-(

> define list_rule_template
> $(1) : $(2)
>         $(OBJDUMP) -h $^ | \
>         sed -n -e 's/.*\(\.u_boot_list[^ ]\+\).*$$/\1/p' | \
>         sed 's/\.[^\.]\+$$//' | \
>         sed -n ':s /^.\+$$/ { p;s/^\(.*\)\.[^\.]*$$/\1/;b s }' | \
>         sed -n 's/\./.#/g;h;s/$$/\a/p;g;s/$$/@/p;g;s/$$/~/p;' | \
>         LC_COLLATE=C sort -u | \
>         sed 's/#//g' | \
>         sed -n -e '/\a$$/ { s/\./_/g;s/\a$$/__start = .;/p; }'\
>                 -e '/~$$/ { s/\./_/g;s/~$$/__end = .;/p; }'\
>                 -e '/@$$/ { s/\(.*\)@$$/*(SORT(\1.*));/p }' >$@
> endef
> ...
> $(eval $(call list_rule_template,$(obj)u-boot.lst,$(LIBBOARD) $(LIBS)))
> ...
> $(eval $(call list_rule_template,$(obj)u-boot-spl.lst,$(LIBS)))
> 
> > +
> > +$(obj)u-boot-spl.lds: $(LDSCRIPT) $(obj)u-boot-spl.lst depend
> > 
> >         $(CPP) $(CPPFLAGS) $(LDPPFLAGS) -ansi -D__ASSEMBLY__ -P - < $< >
> >         $@
> 
> -Joe

[1] http://pubs.opengroup.org/onlinepubs/007908799/xbd/locale.html

Best regards,
Marek Vasut