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Documentation: s390-diag.rst: Document diag500(STORAGE LIMIT) subfunction

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Let's document our new diag500 subfunction that can be implemented by
userspace.

Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20241025141453.1210600-3-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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David Hildenbrand 2024-10-25 16:14:47 +02:00 committed by Heiko Carstens
parent b7cfc04548
commit e5d94902e4
1 changed files with 17 additions and 0 deletions
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Documentation/virt/kvm/s390/s390-diag.rst
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@ -80,6 +80,23 @@ Subcode 3 - virtio-ccw notification
See also the virtio standard for a discussion of this hypercall.
Subcode 4 - storage-limit
Handled by userspace.
After completion of the DIAGNOSE call, general register 2 will
contain the storage limit: the maximum physical address that might be
used for storage throughout the lifetime of the VM.
The storage limit does not indicate currently usable storage, it may
include holes, standby storage and areas reserved for other means, such
as memory hotplug or virtio-mem devices. Other interfaces for detecting
actually usable storage, such as SCLP, must be used in conjunction with
this subfunction.
Note that the storage limit can be larger, but never smaller than the
maximum storage address indicated by SCLP via the "maximum storage
increment" and the "increment size".
DIAGNOSE function code 'X'501 - KVM breakpoint
----------------------------------------------