From mboxrd@z Thu Jan  1 00:00:00 1970
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	<7d1a3207b8e795f9c877a02074e94bf5@hamnavoe.com>
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	<00a9ef8424986e88297b5d4f751e7057@brasstown.quanstro.net>
Date: Fri, 13 Sep 2013 11:16:55 +0300
Message-ID: <CAG3N4d_SOw1-Quoz=P_ZVqAjeihyXEhQPKvJkNnFDt2BL_6CKg@mail.gmail.com>
From: Yaroslav <yarikos@gmail.com>
To: 9fans@9fans.net, 9fans@hamnavoe.com
Content-Type: text/plain; charset=UTF-8
Subject: Re: [9fans] xen3: fresh build 9xenpccpuf dies on boot
Topicbox-Message-UUID: 7f3a309e-ead8-11e9-9d60-3106f5b1d025

Thanks, Erik, your guess is absolutely right... Richard, do you mind
updating /n/sources/xen/xen3/9/xen3/main.c?

term% diff -c /n/sources/xen/xen3/9/xen3/main.c
/n/sources/contrib/yk/xen3/main.c
/n/sources/xen/xen3/9/xen3/main.c:8,13 - /n/sources/contrib/yk/xen3/main.c:8,14
  #include "init.h"
  #include "pool.h"
  #include "reboot.h"
+ #include <tos.h>

  Mach *m;

/n/sources/xen/xen3/9/xen3/main.c:15,20 -
/n/sources/contrib/yk/xen3/main.c:16,26
  #define BOOTARGSLEN (sizeof xenstart->cmd_line)
  #define MAXCONF 64

+ enum {
+ /* space for syscall args, return PC, top-of-stack struct */
+ Ustkheadroom = sizeof(Sargs) + sizeof(uintptr) + sizeof(Tos),
+ };
+
  char bootdisk[KNAMELEN];
  Conf conf;
  char *confname[MAXCONF];
/n/sources/xen/xen3/9/xen3/main.c:270,276 -
/n/sources/contrib/yk/xen3/main.c:276,282
  uchar *av[32];
  uchar **lsp;

- sp = (uchar*)base + BY2PG - MAXSYSARG*BY2WD;
+ sp = (uchar*)base + BY2PG - Ustkheadroom;

  ac = 0;
  av[ac++] = pusharg("/386/9dos");

2013/9/12 erik quanstrom <quanstro@quanstro.net>:
> On Thu Sep 12 09:49:19 EDT 2013, yarikos@gmail.com wrote:
>> > The crash seems to be in init, not the kernel.  Are you sure
>> > your file system image is good?
>>
>> it doesn't get far enough for "root from:", so it seems to fail
>> somewhere in the initcode blob
>
> this may be related to the change put in for the routerboard.
>
> it increased the size of Tos, and thus shifted everything around
> on the stack.  but the old pc kernel didn't account for this, and
> 386 kernels failed with bad arg in syscall.  this never affected the
> pae kernel, or the other architectures.  here's the fix as it went
> into 9atom.
>
> ; 9fs atom
> ; cd /n/atom/plan9/sys/src/9/pc
> ; history -D main.c
> Aug  3 15:30:45 EDT 2013 main.c 16439 [quanstro]
> Aug  3 15:30:45 EDT 2013 /n/atomdump/2013/0912/plan9/sys/src/9/pc/main.c 16439 [quanstro]
> 10a11
>> #include      <tos.h>
> 25a27,31
>> enum {
>>       /* space for syscall args, return PC, top-of-stack struct */
>>       Ustkheadroom    = sizeof(Sargs) + sizeof(uintptr) + sizeof(Tos),
>> };
>>
> 294c300
> <       sp = (uchar*)base + BY2PG - MAXSYSARG*BY2WD;
> ---
>>       sp = (uchar*)base + BY2PG - Ustkheadroom;
>
> - erik



--
- Yaroslav