Is the MIPS kernel buildable from HEAD?

[Patrick Mahan]

> -----Original Message-----
> From: M. Warner Losh [mailto:imp at bsdimp.com]
> Sent: Wednesday, August 25, 2010 10:29 PM
> To: c.jayachandran at gmail.com
> Cc: Patrick Mahan; freebsd-mips at FreeBSD.org
> Subject: Re: Is the MIPS kernel buildable from HEAD?
>
> In message: <AANLkTi=FZrdjE0KoUHvOiB9hyz5ZDWepS9743ghAw9SU at mail.gmail.com>
>             "Jayachandran C." <c.jayachandran at gmail.com> writes:
> : On Thu, Aug 26, 2010 at 2:43 AM, M. Warner Losh <imp at bsdimp.com> wrote:
> : > In message: <32AB5C9615CC494997D9ABB1DB12783C024C875590 at SJ-EXCH-
> 1.adaranet.com>
> : >            Patrick Mahan <PMahan at adaranet.com> writes:
> : > : Is it possible to build the MIPS kernel from HEAD?  Or is the
> : > : current development still external to the HEAD branch?
> : >
> : > Yes.  The tip of head is where the mips action is these days.  There
> : > is no external development branch.
> : >
> : > There is one issue, however.  If you are building for one of the
> : > 64-bit processors a 64-bit kernel, then the required userland won't
> : > build.  There's still issues that need to be sorted out...
> :
> : The 64-bit userland builds for me with  -DWITHOUT_CDDL -DWITHOUT_USB
> : -DWITHOUT_BLUETOOTH  -DWITHOUT_RESCUE - are you referring to these, or
> : are there other issues?
>
> I can do a buildworld now without any of these flags.  I don't know
> what the bluetooth issue is/was, but it doesn't kill the build.  I
> fixed the CDDL issue, and papered over the uath and rescue issues in
> the build system.
>
> I can now build a n64 world in -current.  I haven't had a chance to
> run it yet, but hope to soon.  My CN38xx board doesn't like the 32-bit
> kernel anymore...  It also doesn't like the 64-bit kernel, but I think
> that's a uboot issue.  It seems older ldscripts didn't tickle the bugs
> the current one does (on the other hand, the old ldscripts only worked
> on the CN38xx board).  On the other hand, SDK 1.9.0's uboot on another
> board works fine with the 64-bit kernel.
>

Warner,

We build o32 with our modified FreeBSD 8.0 that boots under the SDK 1.8.1
on a CN58XX.  However, I was looking at the ldscript that we use versus
the one in use for you.  We are using what is basically sys/conf/ldscript.mips.

Also, I think our problem is with the a3 register passed in as part of
platform_start() in cavium/octeon_machdep.c.  We have the following in
mips/lowcore.S -

#if defined(TARGET_OCTEON)
        la      a0, app_descriptor_addr
        sw      a3, 0(a0)               /* Store app descriptor ptr */
#endif

So we are storing the value of a3 into a global that we later use in
octeon32/Octeon_machdep.c -

static void
mips_boot_params_init(void)
{
        int descriptor_not_parsed = 1;

        if ((app_descriptor_addr == 0) || (app_descriptor_addr >= 0xAfffffff)) {
                printf("address of app_descriptor is %x\n",
                    app_descriptor_addr);
        } else {

                app_desc_ptr = (octeon_boot_descriptor_t *) app_descriptor_addr;
                octeon_bd_ver = app_desc_ptr->desc_version;
                ...


I am need to investigate, but I think we found that a3 was getting clobbered on
the inbound call to platform_start().

Patrick