Messages in this thread | | | Date | Thu, 2 Dec 1999 12:00:23 +0100 | From | Pavel Machek <> | Subject | Re: (XFree86) mmap of /proc/XXX/mem |
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Hi!
> > > Yes, but how? We need a solution otherwise we won't be able to > > > use the vm86 mode even on Intel. The emulator makes everything > > > even slower. > > > > Check dosemu. The _real_ problem with /proc/<pid>/mem is that it needs > > very different behaviour in different parts of process address space. Just > > aliasing every page and hoping that extra reference will save your day is > > _very_ bad idea - behaviour of pages on swapout, etc. is determined by > > vma, not by reference in page table. We _might_ go for /proc/<pid>/object/ > > a-la Slowlaris, and that might be made mmap'able, but that's a separate > > story. And IMO an overkill. > > > > Dosemu does aliasing in very similar situation. Check how it's done. > > I don't think dosemu saves my day. It needs just _one_ 1Mb real mode image. > I know how to do that, too. No problem. As I tried to explain in > my original posting I need _several_ 1Mb images: one for each graphics > card. I need to swap them _fast_ without moving around large > chunks of memory. > When another card is selected I could in prinicple copy out the > 1 Meg image of the one previously selected and then copy in the > 1 Meg of the newly selected one. But this is _slow_ compared to > just calling munmap()/mmap() to swap cards. If I only did that > for initialization it's OK. But if I want to do it while the Xserver > is running and in Operating state (ie for updating pallete or > whatever else needs to be done) it is painfully slow. > With mmap() /proc/XXX/mem I can keep all images set up in virtual > address space and only map in the one I need.
Why don't you just prepare 5 files, 1Mega each, and mmap them when you need it? What am I missing? Pavel -- I'm really pavel@ucw.cz. Look at http://195.113.31.123/~pavel. Pavel Hi! I'm a .signature virus! Copy me into your ~/.signature, please!
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