Re: Subject: [RFC PATCH v2 0/8] staging: apfs: init APFS filesystem support

Sven Peter
2025-05-15T16:00:37Z

On Thu, May 15, 2025, at 07:08, Nick Chan wrote:
> Ernesto A. Fernández 於 2025/5/15 凌晨4:19 寫道:
>> Hi Nick,
>>
>> On Tue, May 13, 2025 at 12:13:23PM +0800, Nick Chan wrote:
>>> 2. When running Linux on iPhone, iPad, iPod touch, Apple TV (currently there are Apple A7-A11 SoC support in
>>> upstream), resizing the main APFS volume is not feasible especially on A11 due to shenanigans with the encrypted
>>> data volume. So the safe ish way to store a file system on the disk becomes a using linux-apfs-rw on a (possibly
>>> fixed size) volume that only has one file and that file is used as a loopback device.
>> That's very interesting. Fragmentation will be brutal after a while though.
>> Unless you are patching away the copy-on-write somehow?'
> On a fixed size (preallocated size == max size) volume with only a
> single non-sparse file on it,
> copy-on-write should not happen. I believe the xART volume is also the
> same case with only
> one non-sparse file.

Yeah, the gigalocker file on the xART volume (which is the only file we care about
for eventual Secure Enclave support on M1+ macs) is stored contiguously without
copy-on-write on the disk.

Sven