By: sr (nobody.delete@this.nowhere.com), September 21, 2021 10:48 am
Room: Moderated Discussions
Linus Torvalds (torvalds.delete@this.linux-foundation.org) on September 21, 2021 10:04 am wrote:
> I see the smiley, but segmentation never went away.
>
> And no, it doesn't really fix the problems.
>
> The issue is that fundamentally there is no advantage of a PLB/segmentation
> model over just having the permission in the TLB like people already do.
80386äs MMU was great achievement, it combined both segmentation and paging beautifully together already at 1985. The real problem was that it was not used because it offer possibility to combine all segments to one linear address space. In hindsight was that a mistake?
Is hardware protection against process own code still thought as unneeded? OK we got execution disable bit for data but that is a only little bit taken from possibilities that 386's segmentation unit could do.
> I see the smiley, but segmentation never went away.
>
> And no, it doesn't really fix the problems.
>
> The issue is that fundamentally there is no advantage of a PLB/segmentation
> model over just having the permission in the TLB like people already do.
80386äs MMU was great achievement, it combined both segmentation and paging beautifully together already at 1985. The real problem was that it was not used because it offer possibility to combine all segments to one linear address space. In hindsight was that a mistake?
Is hardware protection against process own code still thought as unneeded? OK we got execution disable bit for data but that is a only little bit taken from possibilities that 386's segmentation unit could do.
| Topic | Posted By | Date |
|---|---|---|
| POWER10 SAP SD benchmark | anon2 | 2021/09/06 03:36 PM |
| POWER10 SAP SD benchmark | Daniel B | 2021/09/07 02:31 AM |
| "Cores" (and SPEC) | Rayla | 2021/09/07 07:51 AM |
| "Cores" (and SPEC) | anon | 2021/09/07 03:56 PM |
| POWER10 SAP SD benchmark | Anon | 2021/09/07 03:24 PM |
| POWER10 SAP SD benchmark | Anon | 2021/09/07 03:27 PM |
| Virtually tagged L1-caches | sr | 2021/09/08 05:49 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/08 08:22 AM |
| Virtually tagged L1-caches | sr | 2021/09/08 08:56 AM |
| Virtually tagged L1-caches | Hugo Décharnes | 2021/09/08 08:58 AM |
| Virtually tagged L1-caches | sr | 2021/09/08 10:09 AM |
| Virtually tagged L1-caches | Hugo Décharnes | 2021/09/08 10:46 AM |
| Virtually tagged L1-caches | sr | 2021/09/08 11:35 AM |
| Virtually tagged L1-caches | Hugo Décharnes | 2021/09/08 12:23 PM |
| Virtually tagged L1-caches | sr | 2021/09/08 12:40 PM |
| Virtually tagged L1-caches | anon | 2021/09/09 03:16 AM |
| Virtually tagged L1-caches | Konrad Schwarz | 2021/09/10 05:19 AM |
| Virtually tagged L1-caches | Hugo Décharnes | 2021/09/10 06:59 AM |
| Virtually tagged L1-caches | anon | 2021/09/14 03:17 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/14 09:34 AM |
| Or use a PLB (NT) | Paul A. Clayton | 2021/09/14 09:45 AM |
| Or use a PLB | Linus Torvalds | 2021/09/14 03:27 PM |
| Or use a PLB | anon | 2021/09/15 12:15 AM |
| Or use a PLB | Michael S | 2021/09/15 03:21 AM |
| Or use a PLB | dmcq | 2021/09/15 03:42 PM |
| Or use a PLB | Konrad Schwarz | 2021/09/16 04:24 AM |
| Or use a PLB | Michael S | 2021/09/16 10:13 AM |
| Or use a PLB | --- | 2021/09/16 01:02 PM |
| PLB reference | Paul A. Clayton | 2021/09/18 02:35 PM |
| PLB reference | Michael S | 2021/09/18 04:14 PM |
| Demand paging/translation orthogonal | Paul A. Clayton | 2021/09/19 07:33 AM |
| Demand paging/translation orthogonal | Michael S | 2021/09/19 09:10 AM |
| PLB reference | Carson | 2021/09/20 10:19 PM |
| PLB reference | sr | 2021/09/20 06:02 AM |
| PLB reference | Michael S | 2021/09/20 07:03 AM |
| PLB reference | Linus Torvalds | 2021/09/20 12:10 PM |
| Or use a PLB | sr | 2021/09/20 04:32 AM |
| Or use a PLB | sr | 2021/09/21 09:36 AM |
| Or use a PLB | Linus Torvalds | 2021/09/21 10:04 AM |
| Or use a PLB | sr | 2021/09/21 10:48 AM |
| Or use a PLB | Linus Torvalds | 2021/09/21 01:55 PM |
| Or use a PLB | sr | 2021/09/22 06:55 AM |
| Or use a PLB | rwessel | 2021/09/22 07:09 AM |
| Or use a PLB | Linus Torvalds | 2021/09/22 11:50 AM |
| Or use a PLB | sr | 2021/09/22 01:00 PM |
| Or use a PLB | dmcq | 2021/09/22 04:07 PM |
| Or use a PLB | Etienne Lorrain | 2021/09/23 08:50 AM |
| Or use a PLB | anon2 | 2021/09/22 04:09 PM |
| Or use a PLB | dmcq | 2021/09/23 02:35 AM |
| Or use a PLB | ⚛ | 2021/09/23 09:37 AM |
| Or use a PLB | Linus Torvalds | 2021/09/23 12:01 PM |
| Or use a PLB | gpd | 2021/09/24 03:59 AM |
| Or use a PLB | Linus Torvalds | 2021/09/24 10:45 AM |
| Or use a PLB | dmcq | 2021/09/24 12:43 PM |
| Or use a PLB | sr | 2021/09/25 10:19 AM |
| Or use a PLB | Linus Torvalds | 2021/09/25 10:44 AM |
| Or use a PLB | sr | 2021/09/25 11:11 AM |
| Or use a PLB | Linus Torvalds | 2021/09/25 11:31 AM |
| Or use a PLB | sr | 2021/09/25 11:52 AM |
| Or use a PLB | Linus Torvalds | 2021/09/25 12:05 PM |
| Or use a PLB | sr | 2021/09/25 12:23 PM |
| Or use a PLB | rwessel | 2021/09/25 03:29 PM |
| Or use a PLB | sr | 2021/10/01 12:22 AM |
| Or use a PLB | rwessel | 2021/10/01 06:19 AM |
| Or use a PLB | David Hess | 2021/10/01 10:35 AM |
| Or use a PLB | rwessel | 2021/10/02 04:47 AM |
| Or use a PLB | sr | 2021/10/02 11:16 AM |
| Or use a PLB | rwessel | 2021/10/02 11:53 AM |
| Or use a PLB | Linus Torvalds | 2021/09/25 11:57 AM |
| Or use a PLB | sr | 2021/09/25 12:07 PM |
| Or use a PLB | Linus Torvalds | 2021/09/25 12:21 PM |
| Or use a PLB | sr | 2021/09/25 12:40 PM |
| Or use a PLB | nksingh | 2021/09/27 09:07 AM |
| Or use a PLB | ⚛ | 2021/09/27 09:02 AM |
| Or use a PLB | Linus Torvalds | 2021/09/27 10:20 AM |
| Or use a PLB | Linus Torvalds | 2021/09/27 12:58 PM |
| Or use a PLB | dmcq | 2021/09/28 10:59 AM |
| Or use a PLB | sr | 2021/09/25 10:34 AM |
| Or use a PLB | rwessel | 2021/09/25 03:44 PM |
| Or use a PLB | sr | 2021/10/01 01:04 AM |
| Or use a PLB | rwessel | 2021/10/01 06:33 AM |
| I386 segmentation highlights | sr | 2021/10/04 07:53 AM |
| I386 segmentation highlights | Adrian | 2021/10/04 09:53 AM |
| I386 segmentation highlights | sr | 2021/10/04 10:19 AM |
| I386 segmentation highlights | rwessel | 2021/10/04 04:57 PM |
| I386 segmentation highlights | sr | 2021/10/05 11:16 AM |
| I386 segmentation highlights | Michael S | 2021/10/05 12:27 PM |
| I386 segmentation highlights | rwessel | 2021/10/05 04:20 PM |
| Or use a PLB | JohnG | 2021/09/25 10:18 PM |
| Or use a PLB | ⚛ | 2021/09/27 07:37 AM |
| Or use a PLB | Heikki Kultala | 2021/09/28 03:53 AM |
| Or use a PLB | rwessel | 2021/09/28 07:29 AM |
| Or use a PLB | David Hess | 2021/09/23 06:00 PM |
| Or use a PLB | Adrian | 2021/09/24 01:21 AM |
| Or use a PLB | dmcq | 2021/09/25 12:41 PM |
| Or use a PLB | blaine | 2021/09/26 11:19 PM |
| Or use a PLB | David Hess | 2021/09/27 11:35 AM |
| Or use a PLB | blaine | 2021/09/27 05:19 PM |
| Or use a PLB | Adrian | 2021/09/27 10:40 PM |
| Or use a PLB | Adrian | 2021/09/27 10:59 PM |
| Or use a PLB | dmcq | 2021/09/28 07:45 AM |
| Or use a PLB | rwessel | 2021/09/28 07:45 AM |
| Or use a PLB | David Hess | 2021/09/28 12:50 PM |
| Or use a PLB | Etienne Lorrain | 2021/09/30 01:25 AM |
| Or use a PLB | David Hess | 2021/10/01 10:40 AM |
| MMU privileges | sr | 2021/09/21 11:07 AM |
| MMU privileges | Linus Torvalds | 2021/09/21 01:49 PM |
| Virtually tagged L1-caches | Konrad Schwarz | 2021/09/16 04:18 AM |
| Virtually tagged L1-caches | Carson | 2021/09/16 01:12 PM |
| Virtually tagged L1-caches | anon2 | 2021/09/16 05:16 PM |
| Virtually tagged L1-caches | rwessel | 2021/09/16 06:29 PM |
| Virtually tagged L1-caches | sr | 2021/09/20 04:20 AM |
| Virtually tagged L1-caches | --- | 2021/09/08 02:28 PM |
| Virtually tagged L1-caches | anonymou5 | 2021/09/08 08:28 PM |
| Virtually tagged L1-caches | anonymou5 | 2021/09/08 08:34 PM |
| Virtually tagged L1-caches | --- | 2021/09/09 10:14 AM |
| Virtually tagged L1-caches | anonymou5 | 2021/09/09 10:44 PM |
| Multi-threading? | David Kanter | 2021/09/09 09:32 PM |
| Multi-threading? | --- | 2021/09/10 09:19 AM |
| Virtually tagged L1-caches | sr | 2021/09/11 01:19 AM |
| Virtually tagged L1-caches | sr | 2021/09/11 01:36 AM |
| Virtually tagged L1-caches | --- | 2021/09/11 09:53 AM |
| Virtually tagged L1-caches | sr | 2021/09/12 12:43 AM |
| Virtually tagged L1-caches | Linus Torvalds | 2021/09/12 11:10 AM |
| Virtually tagged L1-caches | sr | 2021/09/12 11:57 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/13 08:31 AM |
| Virtually tagged L1-caches | sr | 2021/09/20 04:11 AM |
| Virtually tagged L1-caches | sr | 2021/09/11 02:49 AM |
| Virtually tagged L1-caches | Linus Torvalds | 2021/09/08 12:34 PM |
| Virtually tagged L1-caches | dmcq | 2021/09/09 02:46 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/09 02:58 AM |
| Virtually tagged L1-caches | sr | 2021/09/11 01:29 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/11 08:59 AM |
| Virtually tagged L1-caches | sr | 2021/09/12 12:57 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/12 08:44 AM |
| Virtually tagged L1-caches | sr | 2021/09/12 09:48 AM |
| Virtually tagged L1-caches | dmcq | 2021/09/12 01:22 PM |
| Virtually tagged L1-caches | sr | 2021/09/20 04:40 AM |
| Where do you see this information? (NT) | anon2 | 2021/09/09 02:45 AM |
| Where do you see this information? | sr | 2021/09/11 01:40 AM |
| Where do you see this information? | anon2 | 2021/09/11 01:53 AM |
| Where do you see this information? | sr | 2021/09/11 02:08 AM |
| Thank you (NT) | anon2 | 2021/09/11 04:31 PM |