Hi Wolfgang, On Sat, Nov 5, 2011 at 2:53 PM, Wolfgang Denk <w...@denx.de> wrote: > Dear Simon Glass, > > In message > <CAPnjgZ0bbhvZ1VPwY=0y9yzjdf+eobgykkvpfuakbqy2z4l...@mail.gmail.com> you > wrote: >> >> Just a quick Q. What is the ultimate intent here? Should we be aiming >> to have U-Boot copy and decompress the data into RAM ready for Linux? > > Yes. > > Rigth from the beginning of PPCBoot / U-Boot we designed it that > U-Boot would do all needed steps to verify, load and uncompress an > image. It make no sense to attach the uncompression and loading code > to each and every image, and to download it and store it again and > again and again. This works really well for example on Power, only > ARM is one of the examples where the PTB never bothered to acquaint > themself with ideas that went beyond the capabilities of Blob or > similar boot loaders.
OK, it makes sense to me. If U-Boot is doing some unpacking it should do it all IMO. It is supposed to be the boot loader, not half a boot loader. Perhaps for other boot loaders the situation is different. > >> In theory this should be slightly faster since U-Boot already has the >> data in its cache. I think zImage now supports having an FDT inside >> but what is the advantage of zImage over a uImage with compressed >> portions? > > There is none. Also, there is no advantage in attaching the DT blob > to the Linux image/. This is only of use to braindead boot loaders. If so can you please point me to it? Searching for "DTB append ARM zImage" provides lots of recent activity. The justification for this series seems to be old boot loaders. Is there a LKML thread about why it should/shouldn't be done in U-Boot specifically - other boot loaders may require the kernel to do it, but for U-Boot there would need to be some sort of reason I think. I am currently using a hybrid solution (U-Boot loads the zImage and DTB, then kernel decompresses zImage) and we have discussed changing this. It may need a new build target in the kernel, but not rocket science. Regards, Simon > > Best regards, > > Wolfgang Denk > > -- > DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany > Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de > A stone was placed at a ford in a river with the inscription: > "When this stone is covered it is dangerous to ford here." > _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
