Commit 6b392717 authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: map Switcher below fixmap. 



Now we've adjusted all the code, we can simply set switcher_addr to
wherever it needs to go below the fixmaps, rather than asserting that
it should be so.

With large NR_CPUS and PAE, people were hitting the "mapping switcher
would thwack fixmap" message.

Reported-by: default avatarPaul Bolle <pebolle@tiscali.nl>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 6d0cda93

arch/x86/include/asm/lguest.h

+0 −6
Original line number Diff line number Diff line
@@ -14,12 +14,6 @@ 
/* Page for Switcher text itself, then two pages per cpu */

#define TOTAL_SWITCHER_PAGES (1 + 2 * nr_cpu_ids)



/* We map at -4M (-2M for PAE) for ease of mapping (one PTE page). */

#ifdef CONFIG_X86_PAE

#define SWITCHER_ADDR 0xFFE00000

#else

#define SWITCHER_ADDR 0xFFC00000

#endif

/* Where we map the Switcher, in both Host and Guest. */

extern unsigned long switcher_addr;

drivers/lguest/core.c

+5 −10
Original line number Diff line number Diff line
@@ -83,18 +83,13 @@ static __init int map_switcher(void) 
		}

	}



	switcher_addr = SWITCHER_ADDR;



	/*

	 * First we check that the Switcher won't overlap the fixmap area at

	 * the top of memory.  It's currently nowhere near, but it could have

	 * very strange effects if it ever happened.

	 * We place the Switcher underneath the fixmap area, which is the

	 * highest virtual address we can get.  This is important, since we

	 * tell the Guest it can't access this memory, so we want its ceiling

	 * as high as possible.

	 */

	if (switcher_addr + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){

		err = -ENOMEM;

		printk("lguest: mapping switcher would thwack fixmap\n");

		goto free_pages;

	}

	switcher_addr = FIXADDR_START - (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE;



	/*

	 * Now we reserve the "virtual memory area" we want.  We might

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