Re: [Scst-devel] SCST Patch Errors with CentOS 6 2.6.32

[Patrick Z. <pa...@na...>]

Hi,

The put_page_callback_addendum-rhel6 comes from my experience with Fedora 12 (the base OS for RHEL6), and this is supposed to apply cleanly on kernel 2.6.32-71.

I then moved away from CentOS to ScientificLinux 6.1, and the patch doesn't work anymore on the newer kernels (will be the same on CentOS 6.1, once released). This is why we created the new rhel61 patch.

Apart from that, compiling scst/iscsi-scst on rhel6/61 is fairly straightforward.

The best information I've found for rebuilding RHEL kernels actually comes from Fedora:


From: William Cleek [mailto:wil...@gm...] 
Sent: mercredi 28 septembre 2011 20:35
To: Bart Van Assche
Cc: scs...@li...
Subject: Re: [Scst-devel] SCST Patch Errors with CentOS 6 2.6.32



 
On Wed, Sep 28, 2011 at 12:11 PM, Bart Van Assche <bva...@ac...> wrote:
On Wed, Sep 28, 2011 at 1:26 PM, William Cleek <wil...@gm...> wrote:
>> CentOS 6 2.6.32-71.el6.x86_64
>>
>> I have an issue performing the kernel patch step.  I am a less than novice
>> user, so any clear procedural steps on how to get around this will be
>> appreciated.
>>
>>   cd /usr/src/kernels/2.6.32-71.el6.x86_64
>>   patch -p1 <
>> $HOME/scst/iscsi-scst/kernel/patches/put_page_callback-2.6.32.patch
>>   patch -p1 < $HOME/scst/scst/kernel/scst_exec_req_fifo-2.6.32.patch
>>
>>
>> The patch results in multiple of these types of errors.  This occurs on
>> both the iscsi-scst and scst patches.

There are some RHEL 6 / CentOS 6 specific patches in the SCST tree:
$ find -type f|grep rhel
./scst/kernel/rhel/scst_exec_req_fifo-rhel5.patch
./iscsi-scst/kernel/patches/rhel/put_page_callback-rhel5.patch
./iscsi-scst/kernel/patches/rhel/put_page_callback-rhel61.patch
./iscsi-scst/kernel/patches/rhel/put_page_callback_addendum-rhel6.patch

Bart.



Thank you, Bart.  You are correct.  I've spent hours researching different issues related to SCST on CentOS 6.  I've found that there are additional patches, some you mention, that are not in the installation How-To.
Further documentation of this point here:
https://www.centos.org/modules/newbb/viewtopic.php?topic_id=32550
 
 
Also, being a less than novice user I did not download the kernel source.  Duh.
 
Additionally, there is a nasty issue that can arise after patching, related to the patches, but during make.
 
  CC      block/blk-map.o
cc1: warnings being treated as errors
block/blk-map.c: In function â__blk_rq_map_kern_sgâ:
block/blk-map.c:397: error: âresâ may be used uninitialized in this function
 
The solution, as I understand it, requires manual modification of the 
scst_exec_req_fifo patch file
 
Specifically, changing all instances of 
 
int res;
to
int res = -EINVAL;
 
Repatch (to fresh source if necessary as in my case), make again.
http://www.centos.org/modules/newbb/viewtopic.php?topic_id=32371&forum=55

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