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[Xen-devel] Trace buffers no longer working -- What changed?
- To: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
- From: Rob Gardner <rob.gardner@xxxxxx>
- Date: Wed, 08 Mar 2006 13:16:09 -0700
- Delivery-date: Wed, 08 Mar 2006 20:17:00 +0000
- List-id: Xen developer discussion <xen-devel.lists.xensource.com>
It has come to my attention that Xenmon and xentrace have stopped
working in the latest xen-unstable tree, but I'm not sure precisely when
this happened. The problem is that both utilities are failing to map the
xen trace buffers into user space. Anyone have any idea what might have
changed recently that could have caused this? The trace buffer
allocation code in the hypervisor is using alloc_xenheap_pages()
followed by SHARE_PFN_WITH_DOMAIN(), and then the userland apps use
xc_map_foreign_range() to get access to the trace buffers.
xc_map_foreign_range() uses ioctl(IOCTL_PRIVCMD_MMAP) which is failing
with errno 14 (bad address). In particular, the privcmd ioctl uses
direct_remap_pfn_range() which is actually returning the error. I kind
of suspect that there's nothing wrong at the userland side of things,
but something is going wrong when the memory is allocated and "shared".
Can anybody help?
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