---
title: ClaimBuffer
framework: DriverKit
role: symbol
role_heading: Instance Method
path: driverkit/ioextensiblepaniclog/claimbuffer
---

# ClaimBuffer

## Declaration

```occ
virtual kern_return_t ClaimBuffer(uint64_t *addr, uint64_t *len);
```

## Parameters

- `addr`: Address of the mapped buffer
- `len`: The length of the mapped buffer. This is same value as the max_len in the Create() function

## Return Value

Return Value 0 in case of success. Negative in case of an error.

## Discussion

Discussion This function is called to get a pointer to the ext paniclog buffer After this function is called, the user is responsible for copying data into the buffer. The entire buffer is copied when a system panics. After claiming the buffer, YieldBuffer() has to be called to set the used_len of the buffer before calling InsertData() or AppendData()