Re: [Qemu-devel] [PATCH QEMU v1 0/4] multiboot: bss_end_addr can be zero / cleanup

[Jack Schwartz]

Hi Kevin and Anatol.

Kevin, thanks for your review.

More inline below...

On 01/15/18 07:54, Kevin Wolf wrote:
> Am 21.12.2017 um 18:25 hat Jack Schwartz geschrieben:
> > Properly account for the possibility of multiboot kernels with a zero
> > bss_end_addr.  The Multiboot Specification, section 3.1.3 allows for
> > kernels without a bss section, by allowing a zeroed bss_end_addr multiboot
> > header field.
> >
> > Do some cleanup to multiboot.c as well:
> > - Remove some unused variables.
> > - Use more intuitive header names when displaying fields in messages.
> > - Change fprintf(stderr...) to error_report
> There are some conflicts with Anatol's (CCed) multiboot series:
> https://lists.nongnu.org/archive/html/qemu-devel/2017-10/msg03003.html
>
> None if these should be hard to resolve, but it would be good if you
> could agree with each other whose patch series should come first, and
> then the other one should be rebased on top of that.
Anatol,

from my side, there are pros and cons to either patch set going in 
first, but advantages to either are pretty negligible.  Pro for you 
going first: I can use the constants you will define in header files.  
Pro for me going first: your merge should be about the same as if you 
went first (since my changes are small, more localized and affect only 
multiboot.c) and my merge will be easier.

What are your thoughts?
> Testing:
>    1) Ran the "make check" test suite.
>    2) Booted multiboot kernel with bss_end_addr=0.  (I rolled my own
>       grub multiboot.elf test "kernel" by modifying source.)  Verified
>       with gdb that new code that reads addresses/offsets from multiboot
>       header was accessed.
>    3) Booted multiboot kernel with non-zero bss_end_addr.
>    4) Uncommented DEBUG_MULTIBOOT in multiboot.c and verified messages worked.
>    5) Code has soaked in an internal repo for two months.
> Can you integrate your test kernel from 2) in tests/multiboot/ so we can
> keep this as a regression test?
Kevin and alias,

Before I proceed with adding my multiboot test file, I'll clarify here 
that I started with a version from the grub2 tree.  In that file I 
expanded a header file, also from the same tree.  Neither file had any 
license header, though the tree I got them from (Dated October 2017) 
contains the GNU GPLv3 license file.

I'll need to check with my company before I can say I can deliver this 
file.  If I deliver it, I'll add a header stating the GPL license, that 
it came from grub2 and to check its repository for contributors.
> > Jack Schwartz (4):
> >    multiboot: bss_end_addr can be zero
> >    multiboot: Remove unused variables from multiboot.c
> >    multiboot: Use header names when displaying fields
> >    multiboot: fprintf(stderr...) -> error_report()
> Apart from the conflicts, the patches look good to me.
    Thanks,
    Jack
> Kevin