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s390x: change mapping base to allow guests > 2GB 

the current s390x qemu memory layout is

0x1000000: guest start
0x80000000: qemu binary

which limits the amount of available memory to <2GB.
This patch moves the guest pages to 32GB to not collide with the binary
and to leave some space for the program break of qemu.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Christian Borntraeger 2011-05-10 14:49:10 +02:00 committed by Alexander Graf
parent a74cdab44d
commit ff83678aee
1 changed files with 7 additions and 3 deletions
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10
exec.c
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@ -2910,10 +2910,14 @@ ram_addr_t qemu_ram_alloc_from_ptr(DeviceState *dev, const char *name,
#endif
} else {
#if defined(TARGET_S390X) && defined(CONFIG_KVM)
/* XXX S390 KVM requires the topmost vma of the RAM to be < 256GB */
new_block->host = mmap((void*)0x1000000, size,
/* S390 KVM requires the topmost vma of the RAM to be smaller than
an system defined value, which is at least 256GB. Larger systems
have larger values. We put the guest between the end of data
segment (system break) and this value. We use 32GB as a base to
have enough room for the system break to grow. */
new_block->host = mmap((void*)0x800000000, size,
PROT_EXEC|PROT_READ|PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
MAP_SHARED | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
#else
if (xen_mapcache_enabled()) {
xen_ram_alloc(new_block->offset, size);