Message-ID: <4A5C2C42.5030100@msgid.tls.msk.ru>
Date: Tue, 14 Jul 2009 10:57:06 +0400
From: Michael Tokarev <mjt@tls.msk.ru>
Organization: Telecom Service, JSC
User-Agent: Mozilla-Thunderbird 2.0.0.22 (X11/20090706)
MIME-Version: 1.0
To: Pavel Machek <pavel@ucw.cz>
CC: Arnd Bergmann <arnd@arndb.de>, Linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: compat ioctl32 for /dev/snapshot?
References: <49FEB572.4010909@msgid.tls.msk.ru> <20090710162105.GA1469@ucw.cz> <4A592C09.8060104@msgid.tls.msk.ru> <200907121707.11152.arnd@arndb.de> <4A5AD963.5070908@msgid.tls.msk.ru> <20090713202116.GB2569@elf.ucw.cz>
In-Reply-To: <20090713202116.GB2569@elf.ucw.cz>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1936
Lines: 48

Pavel Machek wrote:
[]
>> In order to (try to) check if it works or not, another userspace
>> component has to be fixed to support 32/64 bit mode.  It's uswsusp,
>> which currently assumes swap space structures are all 32bits.  So
>> it isn't possible to immediately check if it works or not -- just
>> ioctl(s) aren't enough.  Complete fix (kernel+user space) requires
>> both, fixing all remaining (yet unknown) issues in old and new
>> code on the way.
> 
> Well, there seems to be single structure in s2disk; that does not seem
> that hard to fix.

Which one do you mean?

Also, do you want to make it 32/64 bit clean in userspace too, so that
an image produced by 32-bit s2disk can be read by 64bit resume and
vise versa?  Sure it's good thing to have, to avoid possible issues
with 32bit initramfs on 64bit system for example...

>> For now, I think it's best to let Pavel or Rafael to decide what
>> to do with all this.
> 
> I don't currently have easy access to 64bit machine, so I guess it is
> up to someone else.
[]

Ok.  I applied Arnd's patch again (with two fixes -- adding
#include <linux/compat.h> and s/compat_ulong/compat_ulong_t/ and
tried suspend/resume cycle with unmodified uswsusp-0.8.  Suspend
worked (seemengly - it reported about 4G pages written, on a
machine with 4G memory) but resume failed after reading all the
pages and submitting them to /dev/snapshot.

I've no time right now to debug it further (and again, yet again:
I don't know the code, neither kernel nor userspace part).

So I'd merge this change for now and deal with possible bugs later.

At least there's no failed ioctl()s on /dev/snapshot anymore,
neither at suspend nor at resume time.

/mjt
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/