4 ms·

> IIUC, safari and other essential OS components are mounted on a read-only volume I... what?

by flangola7 4y ago

deleted 4y ago
[deleted]
pcl 4y ago
If I Understand Correctly
olliej 4y ago
As a basic security measure the macOS system partition is readonly and cryptographically signed. https://support.apple.com/guide/security/signed-system-volume-security-secd698747c9/1/web/1 https://support.apple.com/guide/security/signed-system-volum...
- lern_too_spel 4y ago
  Many other systems, including ostree and Android, have solved this problem years ago. For example, the update can be installed on a read-only cryptographically signed overlay.
zamnos 4y ago
That's right. Safari is an application and so lives under /Applications, which is one a few special directories where the user can make changes, which actually live under /System/Volumes/Data in a scheme similar to unionfs under Linux. Which is to say, / under Catalina and above (so, since 2019), the root partition is really the mount of an APFS snapshot. There's security as a reason, but also from a system perspective, it makes it more robust to upgrade/downgrade OS versions under such a scheme because you always have a known-good system image to revert back to. Safari though is a special case, and so /Applications/Safari.app is a symlink to ../System/Cryptexes/App/System/Applications/Safari.app https://superuser.com/questions/1495124/read-only-file-system-when-i-try-to-touch-in-mac-os-catalina https://superuser.com/questions/1495124/read-only-file-syste...
- olliej 4y ago
  More importantly, it's updating the system WebKit framework, which is a core framework so even if Safari.app was separate, the system framework update forces the reboot. The Safari Technical Previews include their own complete copy of the WebKit framework and link to that (and Safari.app can be made to load WebKit.framework from elsewhere which is how webkit nightlies and from-source builds of webkit can be used)

> IIUC, safari and other essential OS components are mounted on a read-only volume I... what?

deleted 4y ago

[deleted]

pcl 4y ago

If I Understand Correctly

olliej 4y ago

As a basic security measure the macOS system partition is readonly and cryptographically signed. https://support.apple.com/guide/security/signed-system-volume-security-secd698747c9/1/web/1 https://support.apple.com/guide/security/signed-system-volum...

lern_too_spel 4y ago
Many other systems, including ostree and Android, have solved this problem years ago. For example, the update can be installed on a read-only cryptographically signed overlay.

zamnos 4y ago

That's right. Safari is an application and so lives under /Applications, which is one a few special directories where the user can make changes, which actually live under /System/Volumes/Data in a scheme similar to unionfs under Linux. Which is to say, / under Catalina and above (so, since 2019), the root partition is really the mount of an APFS snapshot. There's security as a reason, but also from a system perspective, it makes it more robust to upgrade/downgrade OS versions under such a scheme because you always have a known-good system image to revert back to. Safari though is a special case, and so /Applications/Safari.app is a symlink to ../System/Cryptexes/App/System/Applications/Safari.app https://superuser.com/questions/1495124/read-only-file-system-when-i-try-to-touch-in-mac-os-catalina https://superuser.com/questions/1495124/read-only-file-syste...

olliej 4y ago
More importantly, it's updating the system WebKit framework, which is a core framework so even if Safari.app was separate, the system framework update forces the reboot. The Safari Technical Previews include their own complete copy of the WebKit framework and link to that (and Safari.app can be made to load WebKit.framework from elsewhere which is how webkit nightlies and from-source builds of webkit can be used)