Re: [Xen-API] Issues with XenAPI on CentOS 6.3

[Dave Scott <Dave.Scott@xxxxxxxxxxxxx>]

Hi,

In the broken strace, I can't explain the different sequence of syscalls 
between the file that works (lstat; open) and the file that doesn't (lstat; 
stat; access; open). I also can't reproduce the behaviour you see on my Ubuntu 
with ocaml 3.12.1. Out of curiousity, which ocaml version are you using?

However this is the second time recently we've been bitten by unwanted 
behaviour in the buffered I/O channel code. Since we're dealing with low-level 
stuff like sysfs 'files' where the behaviour of file I/O may not exactly match 
that of regular files, I recommend that we drop down to the low-level Unix.* 
functions which map directly onto syscalls.

Assuming these sysfs files only contain one line of text anyway, how about 
replacing

    read_one_line file

with

    Unixext.string_of_file file

Cheers,
Dave

> -----Original Message-----
> From: xen-api-bounces@xxxxxxxxxxxxx [mailto:xen-api-
> bounces@xxxxxxxxxxxxx] On Behalf Of John Garbutt
> Sent: 07 March 2013 3:03 PM
> To: Mike McClurg
> Cc: xen-api@xxxxxxxxxxxxx
> Subject: Re: [Xen-API] Issues with XenAPI on CentOS 6.3
> 
> Hey Mike,
> 
> Still stuck with these permissions issues when running XAPI on CentOS 6.3
> 
> I have extracted some strace from a standalone OCAML program that works:
> https://gist.github.com/JohnGarbutt/5108513
> 
> I have hacked up XAPIs ballon.ml, there the permissions error occurs, to use
> the above code. The same code as above, when running as part of XAPI, was
> able to read my test file, but was unable to read
> /sys/devices/system/xen_memory/xen_memory0/info/current_kb
> 
> I have managed to capture the strace here, by adding the "-nowatchdog"
> param to xapi:
> https://gist.github.com/JohnGarbutt/5108563
> 
> Any ideas welcome!
> 
> John
> 
> On 1 March 2013 19:37, Mike McClurg <mike.mcclurg@xxxxxxxxxx> wrote:
> > On 01/03/13 17:43, John Garbutt wrote:
> >>
> >> I installed xenopsd using OPAM, not sure how to get hold of the
> >> associated code to check what it is doing.
> >
> >
> > You're probably using the opam remote
> > 'github.com/xen-org/opam-repo-dev/',
> > which tells me...
> >
> > https://github.com/xen-org/opam-repo-
> dev/blob/master/packages/xenopsd.
> > 1.0.0/url
> >
> > ... that the xenopsd repo you've installed is here:
> >
> > git://github.com/djs55/xenopsd.git
> >
> > I'll take a look at your other run-time issue now.
> >
> > Mike
> 
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