lkml.org 
[lkml]   [2007]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    Date
    From
    SubjectRe: [PATCH 6/10] lguest code: the little linux hypervisor.
    On Fri, Feb 09, 2007 at 11:39:31PM +1100, Rusty Russell wrote:
    > On Fri, 2007-02-09 at 11:09 +0100, Andi Kleen wrote:
    > > > +# This links the hypervisor in the right place and turns it into a C array.
    > > > +$(obj)/hypervisor-raw: $(obj)/hypervisor.o
    > > > + @$(LD) -static -Tdata=`printf %#x $$(($(HYPE_ADDR)))` -Ttext=`printf %#x $$(($(HYPE_ADDR)+$(HYPE_DATA_SIZE)))` -o $@ $< && $(OBJCOPY) -O binary $@
    > > > +$(obj)/hypervisor-blob.c: $(obj)/hypervisor-raw
    > > > + @od -tx1 -An -v $< | sed -e 's/^ /0x/' -e 's/$$/,/' -e 's/ /,0x/g' > $@
    > >
    > > an .S file with .incbin is more efficient and simpler
    > > (note it has to be an separate .S file, otherwise icecream/distcc break)
    > >
    > > It won't allow to show off any sed skills, but I guess we can live with that ;-)
    >
    > Good idea, except I currently use sizeof(hypervisor_blob): I'd have to
    > extract the size separately and hand it in the CFLAGS 8(

    hypervisor_start:
    .incbin "hypervisor"
    hypervisor_end:

    ...
    extern char hypervisor_start[], hypervisor_end[];

    size = hypervisor_end - hypervisor_start;




    > > > +static int cpu_had_pge;
    > > > +static struct {
    > > > + unsigned long offset;
    > > > + unsigned short segment;
    > > > +} lguest_entry;
    > > > +struct page *hype_pages; /* Contiguous pages. */
    > >
    > > Statics? looks funky. Why only a single hypervisor_vma?
    >
    > We only have one switcher: it contains an array of "struct
    > lguest_state"; one for each guest. (This is host code we're looking at
    > here).

    This means it is not SMP safe?

    > No, the guest should not be able to evoke a printk from the host kernel.

    This means nobody will know why it failed.

    > > > + else if (i < FIRST_EXTERNAL_VECTOR || i == SYSCALL_VECTOR)
    > > > + setup_idt(lg, i, &d);
    > > > + /* A virtual interrupt */
    > > > + else if (i < FIRST_EXTERNAL_VECTOR + LGUEST_IRQS)
    > > > + copy_trap(lg, &lg->interrupt[i-FIRST_EXTERNAL_VECTOR], &d);\
    > >
    > > switch is not cool enough anymore?
    >
    > It would have to be a switch then gunk at the bottom, because those last
    > two tests don't switch-ify. IIRC I changed back from a switch because
    > of that.

    gcc has a handy extension for this:

    case 0...FIRST_EXTERNAL_VECTOR-1:
    case SYSCALL_VECTOR:
    case FIRST_EXTERNAL_VECTOR...FIRST_EXTERNAL_VECTOR+LGUEST_IRQS:


    Re: the loops; e.g. we used to have possible loop cases
    when a page fault does read instructions and then causes another
    page fault etc.etc. I haven't seen any immediate danger of this,
    but it might be worth double checking.

    -Andi
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-02-09 15:01    [W:0.022 / U:31.876 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site