On Thu, Aug 1, 2019 at 12:34 AM Björn Töpel [off-list ref] wrote:

On Thu, 1 Aug 2019 at 08:59, Andrii Nakryiko [off-list ref] wrote:

quoted

On Wed, Jul 31, 2019 at 8:21 AM Björn Töpel [off-list ref] wrote:

quoted

On Tue, 30 Jul 2019 at 19:43, Kevin Laatz [off-list ref] wrote:

quoted

This patch adds a 'flags' field to the umem_config and umem_reg structs.
This will allow for more options to be added for configuring umems.

The first use for the flags field is to add a flag for unaligned chunks
mode. These flags can either be user-provided or filled with a default.

Signed-off-by: Kevin Laatz <redacted>
Signed-off-by: Ciara Loftus <redacted>

---
v2:
  - Removed the headroom check from this patch. It has moved to the
    previous patch.

v4:
  - modified chunk flag define
---

[...]

quoted

quoted

diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
index 833a6e60d065..44a03d8c34b9 100644
--- a/tools/lib/bpf/xsk.h
+++ b/tools/lib/bpf/xsk.h

@@ -170,12 +170,14 @@ LIBBPF_API int xsk_socket__fd(const struct xsk_socket *xsk);
 #define XSK_UMEM__DEFAULT_FRAME_SHIFT    12 /* 4096 bytes */
 #define XSK_UMEM__DEFAULT_FRAME_SIZE     (1 << XSK_UMEM__DEFAULT_FRAME_SHIFT)
 #define XSK_UMEM__DEFAULT_FRAME_HEADROOM 0
+#define XSK_UMEM__DEFAULT_FLAGS 0

 struct xsk_umem_config {
        __u32 fill_size;
        __u32 comp_size;
        __u32 frame_size;
        __u32 frame_headroom;
+       __u32 flags;

And the flags addition here, unfortunately, requires symbol versioning
of xsk_umem__create(). That'll be the first in libbpf! :-)

xsk_umem_config is passed by pointer to xsk_umem__create(), so this
doesn't break ABI, does it?

Old application, dynamically linked to new libbpf.so will crash,
right? Old application passes old version of xsk_umem_config, and new
library accesses (non-existing) flag struct member.

I think we have similar problems for all the _xattr type of commands
(as well some of btf stuff accepting extra opts structs). How is this
problem solved in general? Do we version same function multiple times,
one for each added field? It feels like there should be some better
way to handle this...

Björn

quoted

quoted

Björn

quoted

 };

 /* Flags for the libbpf_flags field. */
--
2.17.1

_______________________________________________
Intel-wired-lan mailing list
Intel-wired-lan@osuosl.org
https://lists.osuosl.org/mailman/listinfo/intel-wired-lan