Re: Xen 3.3: Problem HVM guest

["Michael Litchard" <michael%schmong.org@localhost>]

Christoph, how did you isolate the problem? I'll take any opportunity
to learn more troubleshooting techniques.

          Michael

On Tue, Aug 12, 2008 at 2:54 PM, Christoph Egger 
<Christoph_Egger%gmx.de@localhost> wrote:
> Christoph Egger wrote:
>>
>> Hi,
>>
>> When launching a HVM guest, the process hangs and does not even block any
>> xmlrpc communication, there's a significant system slowdown until reboot.
>>
>> I finally indentified the place of hang. It is in the xentools33 package
>> in ${WRKSRC}/libxc/xc_hvm_build.c , function setup_guest().
>>
>> At the end of setup_guest(), there's this junk of code:
>>
>>
>>
>>    /* Insert JMP <rel32> instruction at address 0x0 to reach entry point.
>> */
>>    entry_eip = elf_uval(&elf, elf.ehdr, e_entry);
>>    if ( entry_eip != 0 )    {
>>        char *page0 = xc_map_foreign_range(
>>            xc_handle, dom, PAGE_SIZE, PROT_READ | PROT_WRITE, 0);
>>        if ( page0 == NULL )
>>            goto error_out;
>>        page0[0] = 0xe9;               <------------ "hang"
>>        *(uint32_t *)&page0[1] = entry_eip - 5;
>>        munmap(page0, PAGE_SIZE);
>>    }
>>
>>
>> The "hang" happens when executing page0[0] = 0xe9;
>>
>> I'm CC this to tech-kern, because I'm not sure if this is a bug in
>> xentools or if I found a UVM/pmap bug.
>
> Here is an URL to the diff where this hunk has been added including the
> commit log:
>
> http://xenbits.xensource.com/xen-unstable.hg/rev/772674585a1a
>
> Christoph
>
>