From: Chen Zhou <chenzhou10@huawei.com>
Link: https://lkml.org/lkml/2021/1/30/53
Link: 023deaec32
For arm64, the behavior of crashkernel=X has been changed, which
tries low allocation in DMA zone or DMA32 zone if CONFIG_ZONE_DMA
is disabled, and fall back to high allocation if it fails.
We can also use "crashkernel=X,high" to select a high region above
DMA zone, which also tries to allocate at least 256M low memory in
DMA zone automatically (or the DMA32 zone if CONFIG_ZONE_DMA is disabled).
"crashkernel=Y,low" can be used to allocate specified size low memory.
So update the Documentation.
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Tested-by: John Donnelly <John.p.donnelly@oracle.com>
Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Signed-off-by: Kairui Song <kasong@tencent.com>
arm64/crash_core: Export TCR_EL1.T1SZ in vmcoreinfo
TCR_EL1.TxSZ, which controls the VA space size, is configured by a
single kernel image to support either 48-bit or 52-bit VA space.
If the ARMv8.2-LVA optional feature is present and we are running
with a 64KB page size, then it is possible to use 52-bits of address
space for both userspace and kernel addresses. However, any kernel
binary that supports 52-bit must also be able to fall back to 48-bit
at early boot time if the hardware feature is not present.
Since TCR_EL1.T1SZ indicates the size of the memory region addressed by
TTBR1_EL1, export the same in vmcoreinfo. User-space utilities like
makedumpfile and crash-utility need to read this value from vmcoreinfo
for determining if a virtual address lies in the linear map range.
While at it also add documentation for TCR_EL1.T1SZ variable being
added to vmcoreinfo.
It indicates the size offset of the memory region addressed by
TTBR1_EL1.
Kairui Song