Re: [Qemu-devel] qemu softmmu inlined lookup sequence

[Xin Tong]

that is possible. but if that is the case, why not split the tlb
walking and the tlb fill ? can anyone please confirm ?

Xin


2012/4/16 陳韋任 <address@hidden>:
>> > If TLB miss, it will call something like __ldb_mmu (b). __ldb_mmu will try 
>> > to
>> > walk guest page table, then fill TLB entry if page table hit, or raise a 
>> > guest
>> > page fault exception if page table miss.
>>
>> Yep. that is what i was taught. the sequence of code above is an
>> inlined assembly for walking the TLB.  In the __ldx_mmu, the tlb is
>> walked again ? why ?
>>
>>     int index, shift;
>>     target_phys_addr_t ioaddr;
>>     unsigned long addend;
>>     target_ulong tlb_addr, addr1, addr2;
>>
>>     index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
>>  redo:
>>     tlb_addr = env->tlb_table[mmu_idx][index].ADDR_READ;
>>     if ((addr & TARGET_PAGE_MASK) == (tlb_addr & (TARGET_PAGE_MASK |
>> TLB_INVALID_MASK))) {
>>     ...
>>  }
>>
>>   ...
>>   ...
>>   fill_tlb()
>>   ...
>>
>> }
>
>  Perhaps __ldb_mmu is not only called in the TLB lookup sequence, I guess.
> But I am not sure of it.
>
> Regards,
> chenwj
>
>
> --
> Wei-Ren Chen (陳韋任)
> Computer Systems Lab, Institute of Information Science,
> Academia Sinica, Taiwan (R.O.C.)
> Tel:886-2-2788-3799 #1667
> Homepage: http://people.cs.nctu.edu.tw/~chenwj