Hi,
I don''t really understand this, but in xen-2.6.36/dom0/core
there''s this:
% git diff 0c2b1aa4c31830d3b9a40061d1b5f6c8cd837d57
057e5006127460b11e03bf80227881c528b0590d
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 167ca78..0850bd6 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1195,12 +1195,12 @@ asmlinkage void __init xen_start_kernel(void)
pgd = (pgd_t *)xen_start_info->pt_base;
- if (xen_initial_domain())
- __supported_pte_mask |= _PAGE_IOMAP;
- else
+ if (!xen_initial_domain())
__supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD);
__supported_pte_mask |= _PAGE_IOMAP;
+
+ __supported_pte_mask |= _PAGE_IOMAP;
/* Don''t do the full vcpu_info placement stuff until we have a
possible map and a non-dummy shared_info. */
per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
What''s the point of doing the same thing twice at the end? Maybe
it''s
a mis-merge?
--
2. That which causes joy or happiness.
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Josip Rodin
2010-Aug-22 12:13 UTC
[Xen-devel] Re: __supported_pte_mask |= _PAGE_IOMAP twice?
On Sun, Aug 22, 2010 at 02:06:36PM +0200, joy wrote:> Hi, > > I don''t really understand this, but in xen-2.6.36/dom0/core there''s this: > > % git diff 0c2b1aa4c31830d3b9a40061d1b5f6c8cd837d57 057e5006127460b11e03bf80227881c528b0590d > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > index 167ca78..0850bd6 100644 > --- a/arch/x86/xen/enlighten.c > +++ b/arch/x86/xen/enlighten.c > @@ -1195,12 +1195,12 @@ asmlinkage void __init xen_start_kernel(void) > > pgd = (pgd_t *)xen_start_info->pt_base; > > - if (xen_initial_domain()) > - __supported_pte_mask |= _PAGE_IOMAP; > - else > + if (!xen_initial_domain()) > __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD); > > __supported_pte_mask |= _PAGE_IOMAP; > + > + __supported_pte_mask |= _PAGE_IOMAP; > /* Don''t do the full vcpu_info placement stuff until we have a > possible map and a non-dummy shared_info. */ > per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0]; > > > What''s the point of doing the same thing twice at the end? Maybe it''s > a mis-merge?It looks like it, because in: % git diff 3fe0344faf7fdcb158bd5c1a9aec960a8d70c8e8 xen/dom0/core ...that hunk is just: @@ -1031,6 +1066,8 @@ asmlinkage void __init xen_start_kernel(void) if (!xen_initial_domain()) __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD); + __supported_pte_mask |= _PAGE_IOMAP; + #ifdef CONFIG_X86_64 /* Work out if we support NX */ check_efer(); -- 2. That which causes joy or happiness. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Ian Campbell
2010-Aug-22 13:07 UTC
Re: [Xen-devel] __supported_pte_mask |= _PAGE_IOMAP twice?
On Sun, 2010-08-22 at 13:06 +0100, Josip Rodin wrote:> Hi, > > I don''t really understand this, but in xen-2.6.36/dom0/core there''s this: > > % git diff 0c2b1aa4c31830d3b9a40061d1b5f6c8cd837d57 057e5006127460b11e03bf80227881c528b0590d > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c > index 167ca78..0850bd6 100644 > --- a/arch/x86/xen/enlighten.c > +++ b/arch/x86/xen/enlighten.c > @@ -1195,12 +1195,12 @@ asmlinkage void __init xen_start_kernel(void) > > pgd = (pgd_t *)xen_start_info->pt_base; > > - if (xen_initial_domain()) > - __supported_pte_mask |= _PAGE_IOMAP; > - else > + if (!xen_initial_domain()) > __supported_pte_mask &= ~(_PAGE_PWT | _PAGE_PCD); > > __supported_pte_mask |= _PAGE_IOMAP; > + > + __supported_pte_mask |= _PAGE_IOMAP; > /* Don''t do the full vcpu_info placement stuff until we have a > possible map and a non-dummy shared_info. */ > per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0]; > > > What''s the point of doing the same thing twice at the end? Maybe it''s > a mis-merge?Yes, I think its a mismerge. The same thing was in xen/stable-2.6.32.x until recently as well. Ian. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel