Re: pv-grub boot hangs when iommu=soft. Booting kernel directly with the flags works

[Richie <listmail@triad.rr.com>]

Are you able to pv-grub boot while specifying iommu=soft?

To clarify this specific issue; the problem was that minios would 
produce an error message (see example, specifically: port 5 still 
bound!) and fail to boot the kernel.  I suspect if that if you are able 
to boot then the kernel would receive and make use of the parameter as 
it normally would.

# xm create -c ubstub.cfg
> Using config file "/etc/xen/ubstub.cfg".
> Started domain lucidpv (id=2)
> Xen Minimal OS!
>  start_info: 0xa9a000(VA)
>    nr_pages: 0x20000
>  shared_inf: 0xbf44d000(MA)
>     pt_base: 0xa9d000(VA)
> nr_pt_frames: 0x9
>    mfn_list: 0x99a000(VA)
>   mod_start: 0x0(VA)
>     mod_len: 0
>       flags: 0x0
>    cmd_line: (hd0)/boot/grub/menu.lst
>  stack:      0x959980-0x979980
> MM: Init
>      _text: 0x0(VA)
>     _etext: 0x6987c(VA)
>   _erodata: 0x83000(VA)
>     _edata: 0x8bae0(VA)
> stack start: 0x959980(VA)
>       _end: 0x999f88(VA)
>  start_pfn: aa9
>    max_pfn: 20000
> Mapping memory range 0xc00000 - 0x20000000
> setting 0x0-0x83000 readonly
> skipped 0x1000
> MM: Initialise page allocator for ba3000(ba3000)-20000000(20000000)
> MM: done
> Demand map pfns at 20001000-2020001000.
> Heap resides at 2020002000-4020002000.
>  Booting command-list
>
> root  (hd0)
> Filesystem type is ext2fs, using whole disk
> kernel  /boot/vmlinuz-2.6.32.10-xen2  
> root=UUID=2bb30c38-70fc-4e9d-ae69-52db68589a
> 2e ro iommu=soft swiotlb=force
> initrd  /boot/initrd.img-2.6.32.10-xen2
>
> block error -2 for op 2
> close blk: backend=/local/domain/0/backend/vbd/2/51712 node=device/vbd/51712
> port 5 still bound!
>


Bruce Edge wrote:
> On Wed, Apr 7, 2010 at 9:57 AM, Samuel Thibault 
> <samuel.thibault@ens-lyon.org <mailto:samuel.thibault@ens-lyon.org>> 
> wrote:
>
>     listmail, le Wed 07 Apr 2010 12:53:19 -0400, a écrit :
>     > "If the 'iommu=soft swiotlb=force' is removed it boots"
>     >
>     > but in actuality,  "switotlb=force" can be left in and it boots
>     ok as well.
>     > From what I've see it is only when having "iommu=soft" added in that
>     > exposes the issue.
>
>     Ok, so the problem really is the combination of pv-grub and
>     iommu=soft.
>
>
> Any update on this problem?
> I'm assuming that this is related to my inability to pass through PCI 
> devices to a domU when using pv-grub as such requires the use of 
> iommu=soft.
>
> -Bruce
>  
>
>
>     > I understand that you have communicated that you don't have time for
>     > this in near future and I respect that, however, if there is
>     something
>     > specific to try that would shed more light on the issue then let me
>     > know.
>
>     I have no idea off-hand.  In "I don't have time in the near future", I
>     mean that other people could perhaps have a closer look at the
>     issue...
>
>     Samuel
>
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