[dpdk-dev] [PATCH 5/7] mem: modify error message for DMA mask check
Burakov, Anatoly
anatoly.burakov at intel.com
Thu Nov 1 12:12:17 CET 2018
On 01-Nov-18 11:03 AM, Alejandro Lucero wrote:
>
>
> On Thu, Nov 1, 2018 at 10:29 AM Burakov, Anatoly
> <anatoly.burakov at intel.com <mailto:anatoly.burakov at intel.com>> wrote:
>
> On 31-Oct-18 5:29 PM, Alejandro Lucero wrote:
> > If DMA mask checks shows mapped memory out of the supported range
> > specified by the DMA mask, nothing can be done but return an error
> > an report the error. This can imply the app not being executed at
> > all or precluding dynamic memory allocation once the app is running.
> > In any case, we can advice the user to force IOVA as PA if currently
> > IOVA being VA and user being root.
> >
> > Signed-off-by: Alejandro Lucero <alejandro.lucero at netronome.com
> <mailto:alejandro.lucero at netronome.com>>
> > ---
>
> General comment - legacy memory will also need this check, correct?
>
>
> Yes, there is another patch adding this for both, legacy-mem and no-huge
> options.
>
> > lib/librte_eal/common/malloc_heap.c | 35
> +++++++++++++++++++++++++----
> > 1 file changed, 31 insertions(+), 4 deletions(-)
> >
> > diff --git a/lib/librte_eal/common/malloc_heap.c
> b/lib/librte_eal/common/malloc_heap.c
> > index 7d423089d..711622f19 100644
> > --- a/lib/librte_eal/common/malloc_heap.c
> > +++ b/lib/librte_eal/common/malloc_heap.c
> > @@ -5,8 +5,10 @@
> > #include <stddef.h>
> > #include <stdlib.h>
> > #include <stdio.h>
> > +#include <unistd.h>
> > #include <stdarg.h>
> > #include <errno.h>
> > +#include <sys/types.h>
> > #include <sys/queue.h>
> >
> > #include <rte_memory.h>
> > @@ -294,7 +296,6 @@ alloc_pages_on_heap(struct malloc_heap *heap,
> uint64_t pg_sz, size_t elt_size,
> > size_t alloc_sz;
> > int allocd_pages;
> > void *ret, *map_addr;
> > - uint64_t mask;
> >
> > alloc_sz = (size_t)pg_sz * n_segs;
> >
> > @@ -322,11 +323,37 @@ alloc_pages_on_heap(struct malloc_heap
> *heap, uint64_t pg_sz, size_t elt_size,
> > goto fail;
> > }
> >
> > + /* Once we have all the memseg lists configured, if there
> is a dma mask
> > + * set, check iova addresses are not out of range.
> Otherwise the device
> > + * setting the dma mask could have problems with the mapped
> memory.
> > + *
> > + * There are two situations when this can happen:
> > + * 1) memory initialization
> > + * 2) dynamic memory allocation
> > + *
> > + * For 1), an error when checking dma mask implies app can
> not be
> > + * executed. For 2) implies the new memory can not be added.
> > + */
> > if (mcfg->dma_maskbits) {
> > if (rte_mem_check_dma_mask(mcfg->dma_maskbits)) {
> > - RTE_LOG(ERR, EAL,
> > - "%s(): couldn't allocate memory due
> to DMA mask\n",
> > - __func__);
> > + /* Currently this can only happen if IOMMU
> is enabled
> > + * with RTE_ARCH_X86. It is not safe to use
> this memory
> > + * so returning an error here.
>
> I don't think it's RTE_ARCH_X86-only. It can be any other arch with an
> IOMMU that's reporting addressing limitations.
>
>
> Right, but it is just IOMMU hardware from this architecture having the
> current limitation.
> I was trying to just explain why this can happen but I can remove the
> reference to specific
> architecture problems.
>
>
> > + *
> > + * If IOVA is VA, advice to try with
> '--iova-mode pa'
> > + * which could solve some situations when
> IOVA VA is not
> > + * really needed.
> > + */
> > + uid_t user = getuid();
> > + if ((rte_eal_iova_mode() == RTE_IOVA_VA) &&
> user == 0)
>
> rte_eal_using_phys_addrs()?
>
> (the above function name is a bit of a misnomer, it really checks if
> they are available, but not necessarily used - it will return true in
> RTE_IOVA_VA mode if you're running as root)
>
>
> rte_eal_iova_mode returns rte_eal_get_configuration()->iova_mode what
> is set during initialization. It can be PA not just because IOMMU (not
> after the patch)
> but because some PMD does not reports IOVA VA support or because UIO is
> in use.
> Checking for root is because IOVA PA can not be used if non root.
You've misinterpreted my comment.
rte_eal_using_phys_addrs() will effectively return true if you're
running as root. There's no need for an uid check.
The "misnomer" comment was about the rte_eal_using_phys_addrs() - it
reads like it would return false in IOVA_VA mode, but in reality, it
will return true even if IOVA_VA mode - it really should be named
"rte_eal_phys_addrs_available()" rather than
"rte_eal_using_phys_addrs()". This would make it clearer.
>
>
> > + RTE_LOG(ERR, EAL,
> > + "%s(): couldn't allocate
> memory due to DMA mask.\n"
> > + "Try with 'iova-mode=pa'\n",
> > + __func__);
> > + else
> > + RTE_LOG(ERR, EAL,
> > + "%s(): couldn't allocate
> memory due to DMA mask\n",
> > + __func__);
>
> I don't think the error message is terribly descriptive. Looking at it
> through the eyes of someone who sees it for the first time and who has
> no idea what "iova-mode=pa" is, i think it would be more useful to word
> it the following way:
>
> couldn't allocate memory due to IOVA exceeding limits of current DMA
> mask.
> [for non-using phys addrs case] Please try initializing EAL with
> --iova-mode=pa parameter.
>
>
> I'm happy with using your terrific description instead ;-)
> Thanks!
>
> Also, generally newlines in RTE_LOG look ugly unless you indent the
> line :)
>
> > goto fail;
> > }
> > }
> >
>
>
> --
> Thanks,
> Anatoly
>
--
Thanks,
Anatoly
More information about the dev
mailing list