gpoulios commented on PR #16309:
URL: https://github.com/apache/nuttx/pull/16309#issuecomment-2862158650
> @gpoulios why mark the patch to draft?
3 reasons:
- I don't see this getting @raiden00pl 's approval so I thought I'd try
re-writing some parts of the code but it turns out I can't. On the contrary,
I'm thinking of putting back `reg_pair_to_64` and co. as they are [actually
licensed under
BSD](https://github.com/tiiuae/imx-optee-os/blob/8dd180b6d149c1e1314b5869697179f665bd9ca3/lib/libutils/ext/include/util.h#L169).
- I need to guard all list accesses around a mutex. Btw, @xiaoxiang781216
would you rather see this as a new commit or an amendment to the existing one?
- I noticed the IDs in `tee_ioctl_shm_alloc_data`,
`tee_ioctl_shm_register_fd_data`, and `tee_ioctl_shm_register_data` are _all_
output parameters (whereas I was using `rdata.id` as input):
https://github.com/apache/nuttx/blob/468c9eacd8fd30817cd683a07a10ead8d2652a0a/include/nuttx/tee.h#L113
https://github.com/apache/nuttx/blob/468c9eacd8fd30817cd683a07a10ead8d2652a0a/include/nuttx/tee.h#L145
https://github.com/apache/nuttx/blob/468c9eacd8fd30817cd683a07a10ead8d2652a0a/include/nuttx/tee.h#L393
@xiaoxiang781216 Do we really need those? I'm having a hard time generating
unique IDs for shared memory registrations. Thinking of the following options:
1. casting the actual buffer address to int32
- not guaranteed to be unique, either because of 64-bit addresses or due
to overall between user and kernel VA space
2. traversing the list to find a free integer ID starting from 0
- needs at least one list traversal on best case, more if `MAX_INT32`
has been reached
3. using list head's ID + 1
- we need to stick to adding new entries at the head of the list but is
efficient
4. using a `shm_nextid` field in `struct optee_priv_data`
- need to guard with mutex (which I'm also doing for list accesses right
now, so not such a big deal)
Leaning towards 3, but would appreciate your thoughts on this.
On the contrary, points for removing the IDs entirely:
- we can also remove this (correct me if I'm wrong)
https://github.com/apache/nuttx/blob/1a8fba827a73bb842a60f86b610470c2f38ad4f4/drivers/misc/optee.c#L586
- it's not like we can prevent duplicate list entries anyways (especially
given we have both user and kernel registrations).
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