Re: [Xen-devel] [PATCH 3/3] Revert "xen/arm: Allocate memory for dom0 from the bottom with the 1:1 Workaround"

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-04-04 at 15:48 +0100, Julien Grall wrote:
> Hi Ian,
> 
> On 04/04/2014 01:56 PM, Ian Campbell wrote:
> > This reverts commit 6c21cb36e263de2db8716b477157a5b6cd531e1e.
> > 
> > The Linux = issue which this works around was fixed in v3.13 via 
> > f52bb722547f
> > "ARM: mm: Correct virt_to_phys patching for 64 bit physical addresses".
> > 
> > This is the second attempt to revert this. Now that we have fixed
> > allocate_memory_11 to allocate accessible memory on 32-bit this is safe to 
> > do.
> > This is not quite a straight revert since we need to ensure that for 32-bit
> > domain 0 we do not allocate dom0's memory above 4GB where the domain cannot
> > access it without paging (which is disabled at start of day) and LPAE (which
> > the kernel may not support) enabled.
> 
> When multiple banks will be supported, I guess it will be safe to
> allocate above 32bits (if dom0 has more than 4G) of RAM.

Yes. We should aim for as much of dom0's memory as possible to be below
4GB, but if the user asked for more than that we may as well put it
above 4GB and hope that the kernel supports LPAE.

> Anyway, it's not the goal of this patch :).

Yes.

> >  xen/arch/arm/domain_build.c |   16 +++++++++-------
> >  1 file changed, 9 insertions(+), 7 deletions(-)
> > 
> > diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> > index 4d6b26b..e7cc2c9 100644
> > --- a/xen/arch/arm/domain_build.c
> > +++ b/xen/arch/arm/domain_build.c
> > @@ -69,19 +69,21 @@ static void allocate_memory_11(struct domain *d, struct 
> > kernel_info *kinfo)
> >  {
> >      paddr_t start;
> >      paddr_t size;
> > -    struct page_info *pg = NULL;
> > +    struct page_info *pg;
> >      unsigned int order = get_order_from_bytes(dom0_mem);
> >      int res;
> >      paddr_t spfn;
> > -    unsigned int bits;
> >  
> > -    for ( bits = PAGE_SHIFT + 1; bits < PADDR_BITS; bits++ )
> > +    if ( is_32bit_domain(d) )
> >      {
> > -        pg = alloc_domheap_pages(d, order, MEMF_bits(bits));
> > -        if ( pg != NULL )
> > -            break;
> > +        printk("32 bit domain\n");
> 
> [..]
> 
> > +        printk("64 bit domain\n");
> 
> Can you be more explicit on both of theses messages? Nothing specify we
> are allocate memory before them.

ops, those were debugging which I shuld have removed.



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel