Is the extra control necessary, i.e., why not just always do this and let the
EAL option control whether the pages get dumped?
----- On Oct 25, 2024, at 3:26 PM, Dmitry Kozlyuk dmitry.kozl...@gmail.com
wrote:
> It was impossible to include mapped contigmem buffers in core dump.
> Add hw.contigmem.coredump_enable tunable to control the inclusion.
>
> Mappings backed by OBJ_FICTITIOUS are excluded from core dump.
> While contigmem is a device and its OBJT_DEVICE mappings get this flag,
> they are actually backed by memory.
> Clear OBJ_FICTITIOUS mapping bit to include them in core dump.
> Do this only if hw.contigmem.coredump_enable=1.
>
> Signed-off-by: Dmitry Kozlyuk <dmitry.kozl...@gmail.com>
> ---
> doc/guides/freebsd_gsg/build_dpdk.rst | 27 ++++++++++++++++++++-------
> kernel/freebsd/contigmem/contigmem.c | 8 ++++++++
> 2 files changed, 28 insertions(+), 7 deletions(-)
>
> diff --git a/doc/guides/freebsd_gsg/build_dpdk.rst
> b/doc/guides/freebsd_gsg/build_dpdk.rst
> index 86e8e5a805..387ec52820 100644
> --- a/doc/guides/freebsd_gsg/build_dpdk.rst
> +++ b/doc/guides/freebsd_gsg/build_dpdk.rst
> @@ -86,6 +86,22 @@ module loading using::
> kenv hw.contigmem.num_buffers=n
> kenv hw.contigmem.buffer_size=m
>
> +Where n is the number of blocks and m is the size in bytes of each area of
> +contiguous memory. A default of two buffers of size 1073741824 bytes (1
> Gigabyte)
> +each is set during module load if they are not specified in the environment.
> +
> +Buffers are excluded from core dump by default.
> +Mapped buffers can be included in core dump using the following tunable:
> +
> + hw.contigmem.coredump_enable=1
> +
> +.. note::
> +
> + Including contigmem buffers in core dump file increases its size,
> + which may fill the storage or overload the transport.
> + Buffers typically hold data processed by the application,
> + like network packets, which may contain sensitive information.
> +
> The kernel environment variables can also be specified during boot by placing
> the
> following in ``/boot/loader.conf``:
>
> @@ -93,15 +109,12 @@ following in ``/boot/loader.conf``:
>
> hw.contigmem.num_buffers=n
> hw.contigmem.buffer_size=m
> + hw.contigmem.coredump_enable=1
>
> The variables can be inspected using the following command::
>
> sysctl -a hw.contigmem
>
> -Where n is the number of blocks and m is the size in bytes of each area of
> -contiguous memory. A default of two buffers of size 1073741824 bytes (1
> Gigabyte)
> -each is set during module load if they are not specified in the environment.
> -
> The module can then be loaded using kldload::
>
> kldload contigmem
> @@ -115,13 +128,13 @@ up time. This can be achieved by placing lines similar
> to
> the following into
>
> hw.contigmem.num_buffers=1
> hw.contigmem.buffer_size=1073741824
> + hw.contigmem.coredump_enable=1
> contigmem_load="YES"
>
> .. note::
>
> - The contigmem_load directive should be placed after any definitions of
> - ``hw.contigmem.num_buffers`` and ``hw.contigmem.buffer_size`` if the
> default values
> - are not to be used.
> + The ``contigmem_load`` directive should be placed after any definitions
> + of ``hw.contigmem.*`` if the default values are not to be used.
>
> An error such as::
>
> diff --git a/kernel/freebsd/contigmem/contigmem.c
> b/kernel/freebsd/contigmem/contigmem.c
> index 7dd87599d9..591e46dded 100644
> --- a/kernel/freebsd/contigmem/contigmem.c
> +++ b/kernel/freebsd/contigmem/contigmem.c
> @@ -51,6 +51,7 @@ static d_close_t contigmem_close;
>
> static int contigmem_num_buffers =
> RTE_CONTIGMEM_DEFAULT_NUM_BUFS;
> static int64_t contigmem_buffer_size =
> RTE_CONTIGMEM_DEFAULT_BUF_SIZE;
> +static bool contigmem_coredump_enable;
>
> static eventhandler_tag contigmem_eh_tag;
> static struct contigmem_buffer contigmem_buffers[RTE_CONTIGMEM_MAX_NUM_BUFS];
> @@ -59,6 +60,7 @@ static int contigmem_refcnt;
>
> TUNABLE_INT("hw.contigmem.num_buffers", &contigmem_num_buffers);
> TUNABLE_QUAD("hw.contigmem.buffer_size", &contigmem_buffer_size);
> +TUNABLE_BOOL("hw.contigmem.coredump_enable", &contigmem_coredump_enable);
>
> static SYSCTL_NODE(_hw, OID_AUTO, contigmem, CTLFLAG_RD, 0, "contigmem");
>
> @@ -68,6 +70,8 @@ SYSCTL_QUAD(_hw_contigmem, OID_AUTO, buffer_size,
> CTLFLAG_RD,
> &contigmem_buffer_size, 0, "Size of each contiguous buffer");
> SYSCTL_INT(_hw_contigmem, OID_AUTO, num_references, CTLFLAG_RD,
> &contigmem_refcnt, 0, "Number of references to contigmem");
> +SYSCTL_BOOL(_hw_contigmem, OID_AUTO, coredump_enable, CTLFLAG_RD,
> + &contigmem_coredump_enable, 0, "Include mapped buffers in core dump");
>
> static SYSCTL_NODE(_hw_contigmem, OID_AUTO, physaddr, CTLFLAG_RD, 0,
> "physaddr");
> @@ -357,5 +361,9 @@ contigmem_mmap_single(struct cdev *cdev, vm_ooffset_t
> *offset, vm_size_t size,
> *obj = cdev_pager_allocate(vmh, OBJT_DEVICE, &contigmem_cdev_pager_ops,
> size, nprot, *offset, curthread->td_ucred);
>
> + /* Mappings backed by OBJ_FICTITIOUS are excluded from core dump. */
> + if (contigmem_coredump_enable)
> + (*obj)->flags &= ~OBJ_FICTITIOUS;
> +
> return 0;
> }
> --
> 2.38.4
