Posts by arnd@society.oftrolls.com
(DIR) Post #ARPkXCPxaBpZnETXMG by arnd@society.oftrolls.com
2023-01-07T22:46:07Z
0 likes, 0 repeats
Are those distros that require POWER9? I think with the Debian, OpenSUSE and Gentoo ports, the big-endian ppc64 version is kept around for Apple G5, NXP QorIQ and older IBM CPUs but that doesn't stop you from running it on POWER9.Adelie apparently doesn't have a LE port at all, presumably to not need a separate port for newer hardware.
(DIR) Post #ARyZVe2ySIpuqOQLvk by arnd@society.oftrolls.com
2023-01-24T12:16:51Z
0 likes, 0 repeats
@hrw I had to check that my favourite bug is still not fixed: section 3.12 requires that "USB3.0" is implemented using an XHCI, while "USB2.0" is implemented using an EHCI.This is nonsense because USB 2.0 support can be implemented either using a combination of EHCI (for 480Mbit/s) and OHCI (for 1.5 and 12Mbit/s), or just an XHCI (which support all four speeds), but not just an EHCI.
(DIR) Post #ARyZVfIxmLDikGudUW by arnd@society.oftrolls.com
2023-01-24T12:23:02Z
0 likes, 0 repeats
@hrw Having no USB at all is compliant, so that's ok. If an XHCI is added, I think the choice is between only supporting superspeed (in violation of the USB spec), or allowing slower devices on the XHCI in violation of BSA.
(DIR) Post #ATvsODLvQIxcliebz6 by arnd@society.oftrolls.com
2023-03-16T16:07:17Z
0 likes, 0 repeats
It was nice to see everyone yesterday at embedded world in Nürnberg after three years, had a lot of interesting and nice conversations. Here is a summary of some interesting bits I saw.
(DIR) Post #AYiYnXeybXYyYEzaJU by arnd@society.oftrolls.com
2023-08-14T09:51:21Z
0 likes, 0 repeats
@penguin42 A710 has been around for a bit now, and A720 is already here. This one is even more confusing as ARM720 (ARMv4T) is actually still supported by the latest toolchain and kernel releases, unlike the slightly older ARM710 that we dropped back in 2012.Looking forward to Cortex-A920T and Cortex-A926E next.
(DIR) Post #Ahbo0EKebksR93jCl6 by arnd@society.oftrolls.com
2024-04-30T10:09:22Z
0 likes, 0 repeats
@ross @mjg59 On my Apple M1 Ultra, it takes 4.7s to do a sha256 of an 8GB file using openssl, but 26s using coreutils sha256sum. I can see in the perf report that the coreutils version (coreutils 9.1, debian bookworm arm64) does not use the sha256h instructions, but openssl does.
(DIR) Post #AkV3Z88v2oPpu4GgxE by arnd@society.oftrolls.com
2024-07-31T18:15:46Z
0 likes, 0 repeats
Two years ago we deprecated and later removed 80% of the legacy (pre-DT) board files in 32-bit arm kernels after determining that they were most likely unused. Time for the next round.https://lore.kernel.org/linux-arm-kernel/2831c5a6-cfbf-4fe0-b51c-0396e5b0aeb7@app.fastmail.com/T/
(DIR) Post #ApjgeZJD73hQjkyvBI by arnd@society.oftrolls.com
2024-07-23T13:20:57Z
1 likes, 0 repeats
I had a feeling that kernel compilation got slower recently and tried to find the slowest file across randconfig builds. It turned out to be arch/x86/xen/setup.c, which takes 15 seconds to preprocess on a reasonably fast Apple M1 Ultra.This all comes from one line "extra_pages = min3(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)), extra_pages, max_pages - max_pfn);" that expands to 47MB of preprocessor output after commits 80fcac55385c..867046cc70277.
(DIR) Post #ApjgehYkRAsiKGJRVg by arnd@society.oftrolls.com
2024-07-23T18:35:55Z
0 likes, 0 repeats
If anyone wonders what other files are bad, this is the list of all files with over five second compile times: https://pastebin.com/raw/fXJe7y9P.The worst case for this particular file was 44 seconds, three times slower than in defconfig.The median compile time across all files is 0.26s.
(DIR) Post #ApjhGxWdWaaqqbZFXE by arnd@society.oftrolls.com
2024-07-23T16:04:03Z
0 likes, 0 repeats
@KeyJ it nests min() multiple levels deep with the use of min3(), and each one expands its argument 20 times times now (up from 6 back in linux-6.6). This gets 8000 expansions for each of the arguments, plus a lot of extra bits with each expansion. PFN_DOWN(MAXMEM) contributes a bit to the initial size as well.See https://pastebin.com/MmfWH7TM for the first few pages of it.