Hi Andre, On 2 April 2018 at 19:00, André Przywara <andre.przyw...@arm.com> wrote: > Hi, > > On 02/04/18 03:30, Simon Glass wrote: >> >> Hi Andre, >> >> On 2 April 2018 at 09:43, André Przywara <andre.przyw...@arm.com> wrote: >>> Hi, >>> >>> On 01/04/18 14:19, Tom Rini wrote: >>>> On Tue, Mar 27, 2018 at 11:34:19PM +0530, Jagan Teki wrote: >>>>> On Mon, Sep 4, 2017 at 9:57 PM, <s...@google.com> wrote: >>>>>> Hi Tom, >>>>>> >>>>>> On 7 August 2017 at 09:39, Tom Rini <tr...@konsulko.com> wrote: >>>>>>> On Sat, Aug 05, 2017 at 03:45:53PM -0600, Simon Glass wrote: >>>>>>> >>>>>>>> The CONFIG_BLK conversion involves quite invasive changes in the U-Boot >>>>>>>> code, with #ifdefs and different code paths. We should try to move >>>>>>>> over to >>>>>>>> this soon so we can drop the old code. >>>>> >>>>> I hope this will applicable to SPL too? >>>>> >>>>> If so, we are having SPL size issues with few Allwinner families, if >>>>> enable SPL_DM any suggestions? >>>> >>>> How close, and have you looked at the u-boot-spl.map to see what you can >>>> maybe trim? Or areas to look at reducing in code complexity? >>> >>> The Boot ROM limit for all Allwinner SoCs known so far is 32KB. The A64 >>> SPL (AArch64) stands at ~31KB at the moment. Yes, we went over the map >>> and picked most low hanging fruits already. >>> So far we discussed several mitigations, but mostly to cover the >>> "natural" SPL code size grow over time: >>> 1) The AArch64 exception vectors take 1KB, plus an unnecessary ~1.6KB of >>> padding (for a 2KB architectural alignment). Given that the vectors are >>> used only for debugging purposes, we could scrap them entirely or >>> construct them on the fly in some other SRAM. So would free about 2.5KB, >>> ideally. Lowest hanging fruit so far. >>> 2) We can compile the SPL in AArch32 mode, which can use the Thumb2 >>> encoding. This reduces the size significantly, to about 20KB. The >>> disadvantage is using a second cross-compiler or even a additional >>> cross-compiler for native builds, complicating the build process. >>> I maintain a branch for enabling FEL booting here [1], which provides >>> two _defconfigs (one 32-bit for SPL, one 64-bit for U-Boot proper). >>> There are no technical disadvantages in running the SPL in 32-bit, so >>> this is mostly a build issue. >> >> FYI 32-bit tegra compiles SPL with ARMv4T and U-Boot proper with >> ARMv7. It should be fairly easy to do, > > Yes, but this is merely different compiler *flags*, to the same (cross) > compiler binary. ARM32 and ARM64 are different architectures to GCC, so > require different compiler binaries with different prefixes. > Last time I checked this wasn't easy to integrate into the U-Boot build > system. > One hack could be a "switching script", which filters for, say -m32", > and calls the respective binary. But still we need to somehow set *two* > CROSS_COMPILE prefixes. CROSS_COMPILE_SPL, maybe? > But still it would require to install *two* cross compilers, and would > spoil a completely native build by still requiring a cross compiler.
That seems like a good idea to me. > >>> 3) Try to use ILP32 for the AArch64 SPL build. This reduces the pointer >>> size and sizeof(long) to be 32-bit and should help, though I haven't >>> been able to successfully compile it yet (relocation types problems). >>> Despite lacking mainline support for AArch64 ILP32 in Linux and >>> glibc(?), GCC supports it for quite a while already. Unknown saving effect. >>> 4) Use runtime decompression. Most SoCs have larger or more SRAM than >>> the 32KB, so we could leverage this. Siarhei knows more about this. >>> 5) Use a TPL. Haven't looked at this in detail yet. >>> >>> So 1) would be the easiest to pursue, but 2.5KB are not enough to offset >>> the >10 KB toll the DM_SPL support actually takes. >> >> Is this the cost on 64-bit? > > Yes, this is AArch64, just enabling DM_SPL_MMC and DM_SPL. OK I see, and presumably OF_CONTROL as well? > >> I wonder if CONFIG_OF_PLATDATA might be an option? > > Well, this would be a requirement, I guess, since adding any kind of DT > to the mix makes it even worse. Well it still uses DT as the source for the config. It's just that it compiles it to C so we don't have to build in libfdt. It does have some painful side effects though - e.g. you need to adjust drivers to read the new C structure. > > Cheers, > Andre > Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot