RE: [RFC] buildtar: add case for riscv architecture

[Aurabindo Jayamohanan]

âââââââ Original Message âââââââ
On Sunday, September 15, 2019 12:57 AM, Palmer Dabbelt <palmer@xxxxxxxxxx> wrote:

> On Sat, 14 Sep 2019 06:05:59 PDT (-0700), Anup Patel wrote:
>
> > > -----Original Message-----
> > > From: linux-kernel-owner@xxxxxxxxxxxxxxx <linux-kernel-
> > > owner@xxxxxxxxxxxxxxx> On Behalf Of Palmer Dabbelt
> > > Sent: Saturday, September 14, 2019 6:30 PM
> > > To: mail@xxxxxxxxxxxx
> > > Cc: Troy Benjegerdes troy.benjegerdes@xxxxxxxxxx; Paul Walmsley
> > > paul.walmsley@xxxxxxxxxx; aou@xxxxxxxxxxxxxxxxx; linux-
> > > riscv@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-
> > > kbuild@xxxxxxxxxxxxxxx
> > > Subject: Re: [RFC] buildtar: add case for riscv architecture
> > > On Wed, 11 Sep 2019 05:54:07 PDT (-0700), mail@xxxxxxxxxxxx wrote:
> > >
> > > > > None of the available RiscV platforms that Iâm aware of use compressed
> > > > > images, unless there are some new bootloaders I havenât seen yet.
> > > >
> > > > >
> > > >
> > > > I noticed that default build image is Image.gz, which is why I thought its a
> > > > good idea to copy it into the tarball. Does such a copy not make sense at this
> > > > point ?
> > >
> > > Image.gz can't be booted directly: it's just Image that's been compressed
> > > with the standard gzip command. A bootloader would have to decompress
> > > that image before loading it into memory, which requires extra bootloader
> > > support.
> > > Contrast that with the zImage style images (which are vmlinuz on x86), which
> > > are self-extracting and therefor require no bootloader support. The
> > > examples for u-boot all use the "booti" command, which expects
> > > uncompressed images.
> > > Poking around I couldn't figure out a way to have u-boot decompress the
> > > images, but that applies to arm64 as well so I'm not sure if I'm missing
> > > something.
> > > If I was doing this, I'd copy over arch/riscv/boot/Image and call it
> > > "/boot/image-${KERNELRELEASE}", as calling it vmlinuz is a bit confusing to
> > > me because I'd expect vmlinuz to be a self-extracting compressed
> > > executable and not a raw gzip file.
> >
> > On the contrary, it is indeed possible to boot Image.gz directly using
> > U-Boot booti command so this patch would be useful.
> > Atish had got it working on U-Boot but he has deferred booti Image.gz
> > support due to few more dependent changes. May be he can share
> > more info.
>
> Oh, great. I guess it makes sense to just put both in the tarball, then, as
> users will still need to use the Image format for now.
>

Uncompressed vmlinux is already copied by default. This patch just adds the
Image.gz into the archive as vmlinuz. But as you said, since the name vmlinuz is
reserved for self extracting archives, should I keep the original name Image.gz ?