This is an incredible and high quality post. Kudos
Asahi Linux Progress Report: January/February 2021
51–60 of 69 posts
Re: Asahi Linux Progress Report: January/February 2021
#52Does that Trap SMC bit in SYS_APL_HID1_EL1 let you setup a poor man's PSCI even though there's no real EL3? Or is that something different?
And do you think that all those HIDn registers are more PASemi legacy? The PowerPCs are known for HID SPRs being a grab bag of random one off features and chicken bits in a very similar way.
Re: Asahi Linux Progress Report: January/February 2021
#53> Welcome to the first Asahi Linux Progress Report! In this series we’ll be taking a page from the Dolphin playbook and giving you monthly updates on the progress of the project. Nice work! let's see the progress... ~60,000+ words later... > We could keep talking in depth for another 10000 words, but alas, this post is already too long. Please no. A TL;DR is just enough for the busy. The Dolphin report even shows mor…
Well, Dolphin is an emulator, so screenshots and videos are quite an obvious tool to demonstrate game emulation issues... and it's also easier to boil down most changes to "fixes X issue on Y game" for a mature project; that model doesn't map quite as well to the early stages of an OS port project, especially since most of the stuff in this first report is literally required to get anything to work at all. The one sc…
> instead I've been re-visiting and re-working the code into a form that is upstreamable, as well as building tools and chipping away at little details. It's a lot of yak shaving
This is exactly what needs to be done to make this a viable project, and leaving this stuff out is, for me at least, what categorizes Correlium's project as a mere publicity stunt rather than a serious porting effort.
Re: Asahi Linux Progress Report: January/February 2021
#54> On the other hand, the rest of the 64-bit ARM world has largely converged on two competing standards: UEFI + ACPI (largely used by servers running Windows or Linux), It's not supposed to be just for servers, the Arm Base Boot Requirements (BBR) require it for any non-embedded use https://developer.arm.com/documentation/den0044/latest The new ARM64 laptops follow BBR so they have UEFI+ACPI, which means they can run…
It's not really a question of firmware support; the standards need amending to support all of this, and then OSes need to implement core support. Basically, there will never be a way to run Windows natively on Apple Silicon without someone pushing to have a pile of new Apple-specific stuff added to ACPI, and then getting Microsoft to implement support for it. The only way to run Windows on Apple Silicon without all o…
> build their kernels configured for 64K page sizes [...] Presumably they do this for performance on large systems, at the cost of less efficient memory usage.
My guess is that they do that to enable a larger amount of memory (very relevant on servers, which are RedHat's main target market). AFAIK, both the LPA (large physical address) and LVA (large virtual address) extensions, which allow using 52 bits instead of 48 bits for the memory address, require using the 64K page size.
Re: Asahi Linux Progress Report: January/February 2021
#55On a side note. Is there any benefit to a micro kernel operating system anymore?
Linux is a monolithic kernel.
One drive of course, is to have a micro kernel that will allow you to update your operating system as needed, without the need to reboot.
Can this still be accomplished with a micro kernel system, or is this now an obsolete method for operating systems design?
Re: Asahi Linux Progress Report: January/February 2021
#56On a side note. Is there any benefit to a micro kernel operating system anymore? Linux is a monolithic kernel. One drive of course, is to have a micro kernel that will allow you to update your operating system as needed, without the need to reboot. Can this still be accomplished with a micro kernel system, or is this now an obsolete method for operating systems design?
Most of the modularity and security advantages still apply today. Performance is also good, unlike early implementations. Google is developing a microkernel operating system called Fuchsia, possibly to replace Android https://en.wikipedia.org/wiki/Google_Fuchsia
Re: Asahi Linux Progress Report: January/February 2021
#57Ah, the author is here, and leaving feedback here seems easiest -
> Our current Linux bring-up series is in its third version
There's a #fragment in the link, and it goes to a less interesting part of the page. I only circled back after looking at the first and second versions.
Re: Asahi Linux Progress Report: January/February 2021
#58Does that Trap SMC bit in SYS_APL_HID1_EL1 let you setup a poor man's PSCI even though there's no real EL3? Or is that something different? And do you think that all those HIDn registers are more PASemi legacy? The PowerPCs are known for HID SPRs being a grab bag of random one off features and chicken bits in a very similar way.
It still needs to trap to somewhere - e.g. a hypervisor at EL2. But then PSCI can run over HVC anyway, so it doesn't make much of a difference, though being able to pretend EL3 exists from EL2 is nifty. We still lose VM functionality if we run all this at EL2 and the OS at EL1.
I do think the HID register naming scheme comes straight from PowerPC. So does their "DART" IOMMU (again just a name thing, unrelated to the old PowerPC DART IOMMU). A much more interesting question is how much the M1 design directly derives from those older PASemi PPC cores (beyond names and such which could just be a little nod); that's much harder to know, but I'm interested in any hints that might point in that direction :)
Re: Asahi Linux Progress Report: January/February 2021
#59Does that Trap SMC bit in SYS_APL_HID1_EL1 let you setup a poor man's PSCI even though there's no real EL3? Or is that something different? And do you think that all those HIDn registers are more PASemi legacy? The PowerPCs are known for HID SPRs being a grab bag of random one off features and chicken bits in a very similar way.
It still needs to trap to somewhere - e.g. a hypervisor at EL2. But then PSCI can run over HVC anyway, so it doesn't make much of a difference, though being able to pretend EL3 exists from EL2 is nifty. We still lose VM functionality if we run all this at EL2 and the OS at EL1. I do think the HID register naming scheme comes straight from PowerPC. So does their "DART" IOMMU (again just a name thing, unrelated to the…
WRT SMC, I guess I figured it'd be used to put some firmware code in EL2, but not be the exclusive owner of EL2 if that's possible. Cut out a reserved region of mem in m1n1 or u-boot, and an EL2 SMC call would simply be a jump to that code without a mode switch. You'd see that kinda thing in some older ARM RTOSes which would run everything at the same privilege level, but use SWI as a core executive invoke. Of course now that I've typed this all out I realize that I was kinda assuming that there'd be some SMC-hack specific vector table that it could own, but it probably traps to the normal EL2 one which I think is what you're hinting at...
Anyways, is there anything that a systems engineer with RE experience and isn't looking for any of y'all's donations can do to help out? I'm between jobs and it seems like fun.
Re: Asahi Linux Progress Report: January/February 2021
#60On a side note. Is there any benefit to a micro kernel operating system anymore? Linux is a monolithic kernel. One drive of course, is to have a micro kernel that will allow you to update your operating system as needed, without the need to reboot. Can this still be accomplished with a micro kernel system, or is this now an obsolete method for operating systems design?
Most of the modularity and security advantages still apply today. Performance is also good, unlike early implementations. Google is developing a microkernel operating system called Fuchsia, possibly to replace Android https://en.wikipedia.org/wiki/Google_Fuchsia
Is it because of runtime speeds (the slowness) that prevents microkernel operating systems from being more prevalent? Or is it just because Linux is good enough, and it became popular and free?