On Sun, Oct 27, 2019 at 1:32 PM Hauke Mehrtens <ha...@hauke-m.de> wrote: > > On 10/27/19 8:05 PM, Rosen Penev wrote: > > On Sun, Oct 27, 2019 at 10:46 AM Hauke Mehrtens <ha...@hauke-m.de> wrote: > >> > >> This tristate choose allows to select to build only some applications > >> with PIE enabled. On MIPS binaries are getting about 30% bigger when PIE > >> is activated for the, which is a huge increase. > > Some of the size increase can be mitigated with extra compile-time options: > > > > TARGET_CFLAGS += -ffunction-sections -fdata-sections -flto > > TARGET_LDFLAGS += -Wl,--gc-sections,--as-needed > > > > LTO sometimes causes problems but the others should be safe. > > > > PKG_ASLR_PIE applies $(FPIC) to both C and LDFLAGS. I've noticed that > > applying it only to the former increases the size but not as much as > > with both. No idea why. > > Hi Rosen, > > Thank you for the hints. > > I activated -flto for dnsmasq and the size was decreased by 8% which is > nice. I will test this a little bit and then send a patch to the mailing > list. > > The GCC documentation says the following about -pie: > --------------------------------------------------------------------- > -pie > Produce a dynamically linked position independent executable on > targets that support it. For predictable results, you must also specify > the same set of options used for compilation (-fpie, -fPIE, or model > suboptions) when you specify this linker option. > --------------------------------------------------------------------- > https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html#Link-Options > > So we should set it for compiling and linking. > > GCC can activate -flto also when only some of the compile units used > LTO, but it should also be set for both steps.] In my experience, setting -flto is LDFLAGS usually does nothing. CFLAGS is where it makes the difference. But yes, I agree. > > Hauke >
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