We could possibly also do this for struct bio where memdesc_bio returned a more generic type if we added a lower-level MEMDESC_VMPAGES. That would require bloating the type though as you need to store the vm_page_t array pointer (union member), bio_ma_offset, and total size. That said, on LP64 there's already a 4 byte padding hole at the end that could hold bio_ma_offset.

(I had another place that had to duplicate this logic for CCBs and bio's in the NVMF TCP transport layer that generated mbuf chains to describe a memdesc buffer.)

markj accepted this revision.Jul 7 2023, 4:28 PM

This revision is now accepted and ready to land.Jul 7 2023, 4:28 PM

This looks good to me... I'm glad we're reducing the knowledge of CCBs outside of CAM proper.

jhb added a child revision: D41027: memdesc: Replace md_opaque with a union of type-specific fields..Jul 14 2023, 5:38 PM

Closed by commit rG60381fd1ee86: memdesc: Retire MEMDESC_CCB. (authored by jhb). · Explain WhyJul 14 2023, 6:41 PM

This revision was automatically updated to reflect the committed changes.

jhb added a commit: rG60381fd1ee86: memdesc: Retire MEMDESC_CCB..

Hi,
I noticed build failure in _.amd64.FIRECRACKER when giving # make -j6 tinderbox TARGETS=amd64

--- kernel.full ---
linking kernel.full
ld: error: undefined symbol: memdesc_ccb
>>> referenced by subr_bus_dma.c:466 (/usr/src/sys/kern/subr_bus_dma.c:466)
>>>               subr_bus_dma.o:(bus_dmamap_load_ccb)
*** [kernel.full] Error code 1

make[5]: stopped in /usr/obj/usr/src/amd64.amd64/sys/FIRECRACKER
1 error

make[5]: stopped in /usr/obj/usr/src/amd64.amd64/sys/FIRECRACKER
     2079.38 real      1867.10 user       185.11 sys

make[4]: stopped in /usr/src

make[3]: stopped in /usr/src