Re: some possible fixes in the OE web pages

[Martin Jansa <martin.jansa@gmail.com>]

On Thu, May 13, 2010 at 09:53:54AM +0400, Roman I Khimov wrote:
> В сообщении от Четверг 13 мая 2010 01:30:53 автор Robert P. J. Day написал:
> > * on http://wiki.openembedded.net/index.php/OEandYourDistro#Ubuntu,
> > there's a reference to configuring for qemu-arm:
> > 
> >   echo 128 > /proc/sys/vm/mmap_min_addr
> > 
> > from memory, i always simply set that to zero on fedora.  is there
> > something magic about the value 128?  at the moment, it's at the
> > default value of 65536 on this ubuntu system.
> 
> With current qemu in OE mmap_min_addr tricks are not needed at all.

Hi,

On some systems (I have report from fedora and kubuntu) it still needs 0
in mmap_min_addr :/.

Investigating why, but it's slow because it doesn't fail on my box.

My guess is that this chunk from
http://git.qemu.org/qemu.git/tree/linux-user/main.c
cannot work on systems where normal user is not allowed to read 
/proc/sys/vm/mmap_min_addr and mmap_min_addr is not initialized with
sane value.

    /*
     * Read in mmap_min_addr kernel parameter.  This value is used
     * When loading the ELF image to determine whether guest_base
     * is needed.  It is also used in mmap_find_vma.
     */
    {
        FILE *fp;

        if ((fp = fopen("/proc/sys/vm/mmap_min_addr", "r")) != NULL) {
            unsigned long tmp;
            if (fscanf(fp, "%lu", &tmp) == 1) {
                mmap_min_addr = tmp;
                qemu_log("host mmap_min_addr=0x%lx\n", mmap_min_addr);
            }
            fclose(fp);
        }
    }

But here (gentoo) it works ok with 4096 in mmap_min_addr and qemu-native
from OE as well as app-emulation/qemu-kvm-0.12.3* from gentoo.

BTW: 0.12.4 is out, but in changelog I don't see anything I must have.

Regards,

-- 
uin:136542059                jid:Martin.Jansa@gmail.com
Jansa Martin                 sip:jamasip@voip.wengo.fr 
JaMa