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Revision as of 09:07, 1 December 2022 by Deller (Talk | contribs)

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Status & TODO 2022-12-01

  • Kernel: still missing Linux kernel development (no patches available yet or maybe not possible to implement):
    • maybe: optimize flush_dcache_page() implementation like sparc. See Documentation/cachetlb.txt, e.g. used in aio subsystem
    • maybe implement transparent huge pages (due to cache coherency technically only possible on PA8500-PA8700 CPUs, not possible on PA8800-PA8900 CPUs)
    • implement BUG() and WARN() with inline assembly so that interrupt happens in delay branch of "or,<> %r0,cond,%r0". Probably not possible, because gcc will report "control reaches end of non-void function" warnings/errors.
    • disable FP-register save/restore at kernel entry? -
    • enable 16k/64k kernel page sizes (still cacheflushing-issues with SCSI driver, additional work in glibc needed to deal with >4k page size, e.g. ld-loader alignments of data/code segments)
    • Superdome support - can someone test? Should work better now with latest kernels (maybe ask Dennis Clarke <>, Jan 2019).
  • Floating point NaN (see:
    • PA-RISC uses "mips" NaN format which differs from x86, etc. It should be called PA-RISC format as I think PA was first. The quiet NaN bit is opposite to than in current IEEE standard.
    • Debian packages with NaN issues: libime, capnproto
  • palo (PA-RISC Boot Loader):
    • PALO - add regular rewind & load to avoid tftp boot timing issues. See mail from Frank Schreiner "PALO issues" (Dec 2018).
    • When listing directory contents, resolve and print symlink target file names too, e.g. "vmlinux -> linux-5.12.1-64bit".
    • Fix palo deb package to build iplboot natively (
    • Modify (if possible), that palo can read (sequential) tftpbootable-vmlinuxes as well as the current boot-vmlinux images (simplifies build/handling)

Upstream PA-RISC-related kernel patch history

Debian kernel and userspace programs

Debian kernel / Generic Kernel bugs fixed

    • DONE: Fixed 64bit SMP kernel & sticon on machines with more than 4GB RAM (Kernel 3.12)
    • DONE: Lots of syscall fixes regarding compat kernel
    • DONE: send patches to remove UP from debian kernels, use sil680 instead of siimage, see -> fixed in 3.12 / 3.13
    • DONE: Enable BMC in c8000 default kernel config - ipmi driver (CONFIG_IPMI_HANDLER=y) -
    • DONE: remove HIL RTC from debian kernel - it creates a backtrace at boot because we have already another rtc0 active.
    • DONE: add ppdev driver, needed by CUPS, systemd reports missing module load (3.17 & 3.16 kernel)
    • DONE: Add crc-modules, event, isofs, jfs, mouse, sata, sound, squashfs, udf, uinput, scsi-common, scsi-extra, loop, serial and usb-serial debian-installer packages
    • DONE: Kernel build problem: a) disable -mfast-indirect-calls in Makefile, b) gcc compiler bug in > gcc-4.8.3-3
    • DONE: Drop HPUX-support from kernel (Kernel 4.0)
    • DONE: implemented HUGE pages
    • DONE: kernel timerfd_settime/timerfd_gettime issue, test with debian package: liblinux-fd-perl ->, backported to all kernels
    • DONE: kernel ptrace bug:, possible fix:
    • DONE: Implement CONFIG_DEBUG_STACK_USAGE, in kernel 4.6
    • DONE: Use 32bit exception table entries, in kernel 4.6
    • DONE: implemented seccomp syscal, including SECCOMP_MODE_STRICT and mode 2
    • DONE: Fixed FTRACE support (
    • DONE: Add syscall ftrace support
    • DONE: Simplify get_user()/put_user() with regard to %sr0/%sr2 usage.
    • DONE: Add tracehook support (needed for seccomp testcases, gdb, ...)
    • DONE: Added high-resolution sched_clock clocksources in 4.7, needed for debian packages: ismrmrd, haskell-http-conduit, ...
    • DONE: Detect physically broken memory via Page Deallocation Table (PDT), initial support in kernel 4.13
    • DONE: Make kernel self-decompressing (instead of palo reading gzipped kernels)
    • DONE: fix %pF and %pS usage in all kernel code
    • DONE: Enabled BMC/IPMI including Remote power on/off on C8000 and rp3410 machines (kernel 4.17 and above)
    • DONE: use CONFIG_COMPAT_BINFMT_ELF and get rid of arch/parisc/kernel/binfmt_elf32.c
    • DONE: Fix kernel writing core file, gdb reporting: BFD: Warning: /tmp/core.http.1655.ls3011.1465554447 is truncated: expected core file size >= 2187264, found: 2121728.
    • DONE: Find way to extract vmlinux out of vmlinuz (Kernel 4.19)
    • DONE: Implement alternative coding for UP & SMP, one debian kernel for UP and SMP, optimizations to avoid cache flushes on cache-less systems and other qemu-related speed-ups to avoid unnecessary syncronization (Kernel 4.20)
    • DONE: IRQ Balancing was broken,
    • DONE: Added kgdb and kprobes in kernel 5.2, by Sven Schnelle
    • DONE: report on C8000 one socket with 2 cores
    • DONE: Check Kernel boot code if RAM of machine is big enough (e.g. is booting on 710 machine with 60MB possible?) -
    • DONE: convert to SPARSEMEM, instead of DISCONTIGMEM
    • DONE: (NOT POSSIBLE:) Enable huge pages on kernel text for C8000 as well - not possible, will crash due to required equivalent aliasing of caches.
    • DONE: Enable __ro_after_init
    • DONE: add dynamic ftrace support - provided by Sven in kernel 5.3
    • DONE: Fix fallouts from strace:,
    • DONE: implement kexec syscall
    • DONE: Analyze futex hang (CPU soft lockup) situation with test-lock testcase in the libprelude debian package - fixed by parisc: Add atomic64_set_release() define to avoid CPU soft lockups
    • DONE: Add TOC handler, sending TOC via IPMI interface "toc s"
    • DONE: autofs/automounter is broken, patch sent to list,
    • DONE: Try enabling DEBUG_VM_PGTABLE in kernel
    • DONE: SLAB breaks, SLUB works (works in kernel v5.17)
    • DONE: implement .con_font_set (consw) in sticon.c to be able to change fonts at runtime (since v5.10)
    • DONE: Implement kernel VDSO support - Randolphs patch

ABI breakages (e.g. dropped HP-UX support)

Considerations between Debian unstable and Debian Jessie release

Jessie was not stable on SMP machines, particularly those with PA8800/PA8900 processors. It's recommended to use kernel 4.4.15 or later. The current default gcc for unstable is gcc 5.4. Most hppa fixes have been back ported to 4.9 but not all. It shouldn't hurt to use binutils from unstable. Debian glibc 2.23 is best. Most old packages should still work although there maybe inequivalent aliasing issues which are relevant on PA8800. There's also a nasty issue with gmon_start being in every shared library in Jessie. This caused a few headaches and potentially breaks applications when it's removed from a library. If you stick with the glibc in Jessie, multithreaded applications may not work as well as they could, but maybe that's not important. The kernel update is the most important one. Since hppa moved to ports, there has been a huge number of bug fixes. System stability is dramatically improved and I believe more packages are available than ever before. It's better to run unstable and just be selective about running "apt-get upgrade". (by Dave Anglin) Homepage and Debian build server infrastructure work

Linus Torvalds barking at parisc

Testsuites, kernel and userspace testing tools

TODO Drivers

  • write Lasi floppy driver
  • write Suckyio floppy driver
  • write spifi driver (rbrad)
  • modify ncr53c8xx driver for Outfield (735 & 755)
  • write GSC FDDI driver
  • write Timi ASIC (74x) support
  • EISA DMA support

Review all the todo entries below!

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