Messages in this thread | | | Date | Tue, 27 Sep 2005 15:32:19 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH][Fix] Fix Bug #4959 (take 2) |
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Hi!
I do not really like new exports from swsusp.c, but I'm afraid there's no way around.
> The following patch fixes Bug #4959. For this purpose it creates temporary > page translation tables including the kernel mapping (reused) and the direct > mapping (created from scratch) and makes swsusp switch to these tables > right before the image is restored.
Why do you need *two* mappings? Should not just kernel mapping be enough?
> NOTES: > (1) I'm quite sure that to fix the problem we need to use temporary page > translation tables that won't be modified in the process of copying the image. > (2) These page translation tables have to be present in memory before the > image is copied, so there are two possible ways in which they can be created: > (a) in the startup kernel code that is executed before calling swsusp > on resume, in which case they have to be marked with PG_nosave, > (b) in swsusp, after the image has been loaded from disk (to set up > the tables we need to know which pages will be overwritten while > copying the image). > However, (a) is tricky, because it will only work if the tables are always located > at the same physical addresses, which I think would be quite difficult to achieve.
Why? Reserve ten pages for them... static char resume_page_tables[10*PAGE_SIZE] does not sound that bad.
> Moreover, such a code would have to be executed on every boot and the > temporary page tables would always be present in memory.
Yep, but I do not see that as a big problem.
-- 64 bytes from 195.113.31.123: icmp_seq=28 ttl=51 time=448769.1 ms
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