From: "Brian L. Stuart" <blstuart@bellsouth.net>
To: <9fans@9fans.net>
Subject: [9fans] Plan9 on Pi 3B+
Date: Tue, 3 Apr 2018 18:52:28 +0000 [thread overview]
Message-ID: <1092190499.1253166.1522781548163@mail.yahoo.com> (raw)
In-Reply-To: <1092190499.1253166.1522781548163.ref@mail.yahoo.com>
Has anyone tried Plan 9 on the new Pi 3B+? I've
run into something that confuses me a bit. First,
it seems you need the new version of start_cd.elf
to bring up the 3B+. However, with that, the kernel
throws a lock loop error. In tracking down the loop,
it happens in startcpus() in archbcm2.c. The code
here looks like:
for(i = 0; i < ncpu; i++)
lock(&startlock[i]);
cachedwbse(startlock, sizeof startlock);
for(i = 1; i < ncpu; i++) {
if(startcpu(i) < 0)
return i;
lock(&startlock[i]);
unlock(&startlock[i]);
}
So we grab a lock on all the CPUs, then drop into
a second loop where we start CPUs 1 to n. But
in that loop we grab the lock again and then
immediately unlock it. This is where the lock
loop happens. Everything seems to continue
to be happy on both a 2 and a 3B+ if I comment
out the lock in the second loop. But what is the
rationale for the lock in the second loop? Was
there a reason for putting it there, or was it an
oversight that wasn't exposed until the new boot
code?
Thanks,
BLS
next parent reply other threads:[~2018-04-03 18:52 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1092190499.1253166.1522781548163.ref@mail.yahoo.com>
2018-04-03 18:52 ` Brian L. Stuart [this message]
2018-04-03 19:35 ` Erik Quanstrom
2018-04-03 21:05 ` Richard Miller
2018-04-04 0:30 ` Skip Tavakkolian
2018-04-05 14:17 ` Richard Miller
2018-04-05 15:03 ` Richard Miller
2018-04-05 17:02 ` Steve Simon
2018-04-05 20:25 ` Bakul Shah
2018-04-05 22:13 ` hiro
2018-04-05 22:40 ` Rui Carmo
2018-04-05 21:33 ` Richard Miller
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1092190499.1253166.1522781548163@mail.yahoo.com \
--to=blstuart@bellsouth.net \
--cc=9fans@9fans.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).