"Magnus Damm" <[EMAIL PROTECTED]> writes: > Hi guys, > > Please excuse the long delay. I've been on vacation/offline. > > On 6/8/06, Vivek Goyal <[EMAIL PROTECTED]> wrote: >> >> I think Eric is talking of only to allocate page_table_a statically. > > On x86_64 the size of page_table_b varies with the amount of physical > memory so it is probably a good idea to allocate these pages on > demand.
Agreed, page_table_b the existing table makes sense to allocate dynamically. >> I think CONFIG_PHYSICAL_START should not be a problem. You anyway will >> switch to page_table_b before you start copying the pages and overwrite >> the previous kernel's text section. Kernel also should not set up >> DMA to these statically allocated pages so there is no problem in >> allocating page_table_a statically AFAIKS. > > You are right, there should be no problem with DMA. > >> I don't know what are the advantages of static allocation. Eric >> can throw some light. > > I'd like to hear the advantages. It is simple because it is all constants. And it removes the need for additional infrastructure. Which for an incremental patch is a huge win. Allowing us to address one concern at a time. > Right now I can only see the disadvantages of static allocation. If > page_table_a is statically allocated 7/5/3 pages will be consumed on > x86_64/i386+PAE/i386. I'd like to stay away from eating 12-28 Kbytes > of kernel memory statically (= at boot time) without any special > reason. Yes. It is a measurable amount of memory. However it is not so much that it is prohibitive, and for everyone using the feature it is not a waste of memory :) > Let me know what you think and I will rewrite and break out the code. I just want a simple starting point so we can look at one issue at a time. Once we have sorted through what we need in the trivial page table then we can discuss changing our allocation policy of it to be dynamic. Eric _______________________________________________ fastboot mailing list [email protected] https://lists.osdl.org/mailman/listinfo/fastboot
