Re: [Xen-devel] Re: mini-os for Xen2

[Rick <judicator3@xxxxxxxxx>]

Hi Keir,

You were right, I was missing the section __xen_guest.
So now when I create the domain I do not get any error message and I
do get a console.
So the 1st thing I am doing is just trying to write something on the
console with the hypervisor call "console_io". However, I do not see
anything on the console. In order to use the hypervisor calls, do I
have to first set up the trap tables, page tables and parse the shared
struct info etc ... ?  Also, is it important where I load the image ?
Right now my lds script specifies "0xC0000000" as the starting
address. I also tried "0xC0000000 + 0x100000" which I saw in the linux
lds script.

My head.S file is very simple and I invoke the hypervisor calls by
issuing the interrupts directly:

#define ENTRY(X) .globl X ; X :

.section __xen_guest
        .ascii"GUEST_OS=linux,GUEST_VER=2.6,XEN_VER=2.0,VIRT_BASE=0xC0000000"
        .ascii  ",LOADER=generic"
        .ascii  ",PT_MODE_WRITABLE"
        .byte   0

.text

/*
 * References to members of the new_cpu_data structure.
 */

        .globl _start
_start:
        cld


        movl    $18,%eax                        # __HYPERVISOR_console_io
        movl    $0, %ebx                         #  arg1 = 0 for write  
        movl    $hello_message_len,%ecx #  arg2 = buffer length
        movl    $hello_message,%edx       #  arg3 = buffer virtual address
        int     $0x82

        
        movl    $6,%eax                 # __HYPERVISOR_sched_op
        movl    $2,%ebx                 # shutdown
        int     $0x82

hang:   jmp     hang                    # shouldn't get here


hello_message:  .ascii  "This is the hello world program\n"
hello_message_len = . - hello_message


Thanks
Richard



On Sat, 12 Feb 2005 18:39:07 -0800, Jacob Gorm Hansen <jacobg@xxxxxxx> wrote:
> Keir Fraser wrote:
> > xm gives the world's most unhelpful error messages. You may well find
> > a more useful message hidden away in /var/log/xend[-debug].log as
> > comes straight from the domain builder in libxc.
> >
> > My guess woul dbe that you do not have a '__xen_guest' section in your
> > Elf image. Look at the top of
> > linux-2.6.10-xen-sparse/arch/xen/i386/kernel/head.S for an example of
> > how to specify one.
> >
> 
> The new vm-tools that were just announced will probably be easier to use
> for this kind of debugging than xn/xend. Also, I used to re-create the
> HYPERVISOR_console_write syscall, and configure Xen to allow unpriv
> domains to write to the serial console. I think the new
> HYPERVISOR_console_io syscall can be convinced to do the same thing.
> 
> In my xen tarball at http://www.diku.dk/~jacobg/self-migration/ you can
> find the source of 'mstrap' which is very much like mini-os, but perhaps
> a little more up to date. The network driver is not working in Xen2, but
> the elf-image should at least load using the recent tools.
> 
> Jacob
>


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