3 ms·
I assume TLB is translation lookaside buffer, but what do you mean by "soft fill" here?
by packetlost 3y ago
I assume TLB is translation lookaside buffer, but what do you mean by "soft fill" here?
- Veserv 3y agoThey mean software-filled. On “page fault (really a illegal memory access)” you walk a software data structure to determine if there should actually be accessible memory there then you “page in (update the MPU to make the memory accessible, possibly evicting another entry)” the memory. This is how some older chips used to work. Hardware page table walkers can be viewed as just a hardware implementation of such code.
- chc4 3y agoI was horrified to learn that PowerPC uses an "inverted page table", which is essentially just a TLB implemented as a hash table. If the requested page isn't resident in the inverted page table it delivers an interrupt, where the kernel is supposed to walk it's own internal internal page table data structure and populate the hash table entry for the missing page. It was a big surprise coming from x86 or ARM on personal computer kernels where they have a fully populated page table as the canonical source of mappings, and all walking in hardware!
- saagarjha 3y agoIt does let you do some cute things in the software implementation though. I’d prefer a hardware walk of course but if I can’t have it might as well enjoy things.