[U-Boot] Relocation size penalty calculation

J. William Campbell
2009-10-08T15:58:26Z

Graeme Russ wrote:
> Out of curiosity, I wanted to see just how much of a size penalty I am
> incurring by using gcc -fpic / ld -pic on my x86 u-boot build. Here are
> the results (fixed width font will help - its space, not tab, formatted):
>
> Section non-reloc reloc
> ---------------------------------------
> .text 000118c4 000137fc <- 0x1f38 bytes (~8kB) bigger
> .rodata 00005bad 000059d0
> .interp n/a 00000013
> .dynstr n/a 00000648
> .hash n/a 00000428
> .eh_frame 00003268 000034fc
> .data 00000a6c 000001dc
> .data.rel n/a 00000098
> .data.rel.ro.local n/a 00000178
> .data.rel.local n/a 000007e4
> .got 00000000 000001f0
> .got.plt n/a 0000000c
> .rel.got n/a 000003e0
> .rel.dyn n/a 00001228
> .dynsym n/a 00000850
> .dynamic n/a 00000080
> .u_boot_cmd 000003c0 000003c0
> .bss 00001a34 00001a34
> .realmode 00000166 00000166
> .bios 0000053e 0000053e
> =======================================
> Total 0001d5dd 00022287 <- 0x4caa bytes (~19kB) bigger
>
> Its more than a 16% increase in size!!!
>
> .text accounts for a little under half of the total bloat, and of that,
> the crude dynamic loader accounts for only 341 bytes
>
Hi Graeme,
I would be interested in a third option (column), the x86 build
with just -mrelocateable but NOT -fpic. It will not be definitive
because there will be extra code that references the GOT and missing
code to do some of the relocation, but it would still be interesting.

Best Regards,
Bill Campbell
> Have any metrics been done for PPC?
>
> Regards,
>
> Graeme
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