Re: building e2k qemu errors

[Peter Maydell]

On Thu, 26 May 2022 at 18:14, Joe Nosay <superbisquit@gmail.com> wrote:
>
> The errors occur at the end of the attached file.

...which is to say:

../net/eth.c: In function ‘eth_parse_ipv6_hdr’:
../net/eth.c:410:15: error: array subscript ‘struct
ip6_ext_hdr_routing[0]’ is partly outside array bounds of ‘struct
ip6_ext_hdr[1]’ [-Werror=array-bounds]
  410 |     if ((rthdr->rtype == 2) &&
      |          ~~~~~^~~~~~~
../net/eth.c:487:24: note: while referencing ‘ext_hdr’
  487 |     struct ip6_ext_hdr ext_hdr;
      |                        ^~~~~~~
../net/eth.c:411:15: error: array subscript ‘struct
ip6_ext_hdr_routing[0]’ is partly outside array bounds of ‘struct
ip6_ext_hdr[1]’ [-Werror=array-bounds]
  411 |         (rthdr->len == sizeof(struct in6_address) / 8) &&
      |          ~~~~~^~~~~
../net/eth.c:487:24: note: while referencing ‘ext_hdr’
  487 |     struct ip6_ext_hdr ext_hdr;
      |                        ^~~~~~~
../net/eth.c:412:15: error: array subscript ‘struct
ip6_ext_hdr_routing[0]’ is partly outside array bounds of ‘struct
ip6_ext_hdr[1]’ [-Werror=array-bounds]
  412 |         (rthdr->segleft == 1)) {
      |          ~~~~~^~~~~~~~~
../net/eth.c:487:24: note: while referencing ‘ext_hdr’
  487 |     struct ip6_ext_hdr ext_hdr;
      |                        ^~~~~~~


These are fixed in upstream commit 7d6a4f123e00c9, which
went into QEMU a year ago (should be in QEMU 6.1, I think).

In general this kind of situation where a newer compiler
is better at identifying and warning about problems can
happen where you're building an older QEMU with a newer
compiler that hadn't been released at the time that the
QEMU you're building was released. There are three basic
ways to resolve it:

(1) use a newer QEMU
(2) use an older compiler
(3) if the problem is only a warning, configure QEMU with
    --disable-werror so it isn't fatal. (Looks like for
    this specific case that wouldn't help, though.)

thanks
-- PMM