Re: [Qemu-devel] [PATCH v2] PAM: make PAM emulation closer to documentation

[Ефимов Василий]

21.07.2015 10:46, Paolo Bonzini пишет:

> Out of curiosity, would it be necessary to flush the TLB when the PAM
> registers change?
>
> In QEMU, the TLB also has the function of a cache in some sense
> (because, by pointing to a ram_addr_t, it prevents reads, writes or
> fetches from going through the slow MMIO path).
There is exec.c: tcg_commit callback. It calls
cpu-exec.c: cpu_reload_memory_map that calls cputlb.c:tlb_flush.

When PAM register is changed pam_update is called. Its call is
surrounded by memory_region_transaction_begin/_commit couple both in
i440fx and MCH9 host bridges. tcg_commit and pam_mem_commit are called
during memory_region_transaction_commit execution.

To summarize:
- TLB is flushed by existing code.
- Should I remove pam_update_redirection call from pam_set_current?
It will be called by pam_mem_commit soon? Note that a PAM API user
should call memory_region_transaction_begin/_commit in this case.
> Paolo
Vasily