On 1/20/25 17:38, Zhao Liu wrote:
Thanks for the reminder, yes it is currently full. I found I missed
a commnet from Paolo [*], that he suggested only convert `unspecified`
to a bool. My bad :-(
It still raises the size to 8 bytes but saves spare space, like:
typedef struct MemTxAttrs {
unsigned int secure:1;
unsigned int space:2;
unsigned int user:1;
unsigned int memory:1;
unsigned int requester_id:16;
unsigned int pid:8;
bool unspecified;
uint8_t _reserved1;
uint16_t _reserved2;
} MemTxAttrs;
Similar to your comment above, to get pakced structure, I think I need
push `unspecified` field down to other bit fields.
Right, this would allow for a 16-bit PASID, 19 free bits and no QEMU_PACKED:
typedef struct MemTxAttrs {
bool unspecified;
uint8_t int secure:1;
uint8_t int space:2;
uint8_t int user:1;
uint8_t memory:1;
uint16_t requester_id;
uint16_t pid;
uint16_t _reserved;
} MemTxAttrs;
QEMU_BUILD_BUG_ON(sizeof(MemTxAttrs) > 8);
Together with const_zero!() that would be fine for both C and Rust, and
a bit more efficient too.
Paolo
