On 1/11/21 8:55 AM, chase rayfield wrote: > On Mon, Jan 11, 2021 at 3:09 AM John Paul Adrian Glaubitz > <glaubitz@xxxxxxxxxxxxxxxxxxx> wrote: > >> >> I'm not sure I understand the reasoning for doing this. The SPARC architecture >> isn't going to see any new hardware developments in the future after Oracle >> let go of most of the SPARC developers. So it's not that we need to make room >> for new hardware. >> > My take is that there *would* be more interest in Sparc sun4m / Sun4d > from enthusiasts at the very least if it was possible to actually boot > the bloat hog that is Linux these days in a fully usable configuration > that probably means some modifications to SILO and Linux required. You can trim current linux down a bit, it's just non-obvious how. Unfortunately there's an "expert" menu and CONFIG_EMBEDDED and if you touch anything there's suddenly a hundred extra options in your config with no explanation of what they do. At least 50% of what you want is probably disabling the printk strings that aren't visible at your default verbosity level, but alas you must open pandora's box to access those options... > The problem is as I understand it, SILO only sets up a 16Mb mapping > (either due to having to assume 4MB minimum dram stick size or due to > mapping limitations not sure, most of these machines have at least > 16MB in slot one...these days though that wasn't the case for sun4c), > loads Linux into it and says good Luck. This isn't enough for a modern > kernel with any hardware support built in. So you might for instance > get a kernel to fit but only if you dropped all of networking support > etc... I'm guessing the fix for this would be to modify silo to map a > larger amount in a way that Linux expects so it can remap it as it > likes, or just have SILO map the full memory as Linux would. Anyway > that is THE main demotivation for these architectures.... otherwise > they have plenty of ram and performance to do basic router/server > tasks sans SSL. A lot of people with hardware like this haven't stopped using it, they've just stopped fighting with kernel upgrades. (Common issue in the embedded world. Not really a fun thing for security, but ) > This has been the status quo for since the last of the 2.6 series of > kernels which it was still possible to just barely squeeze a usable > kernel out of... If someone wanted to take a few hours and fix this > issue, and keep these architectures around I'd be happy to "buy them a > round of pizza", though I recognize that many people that work on this > already have nice jobs, and just don't have time. My https://github.com/landley/toybox/blob/master/scripts/mkroot.sh ~250 line bash script generates the simplest kernel configs for a bunch of platforms to boot qemu to a shell prompt, but you then have to open the "expert" menu and _disable_ stuff in order to get the size down from there. > Also Sparc would probably be a good project for someone to extend/test Sparc has a runtime relocation I've never understood but did manage to break once, resulting in a long thread to fix: http://lists.landley.net/pipermail/aboriginal-landley.net/2011-December/001964.html Between that and the weird save half the stack register thing with function calls on some sort of "wheel"... there's a _reason_ I haven't been able to talk Rich into adding support for it to musl. > Andi Keen's Linux LTO patch set so we could reduce the kernel binary > size that way also even if sun4 architectures are dropped, it would > still be useful for embedded sparc. Also there is a port of Temlib to > the Mister hardware now, 3 cores roughly equivalent to a mid 90s > machine, at least 128MB ram is possible ( more if a way to map the ARM > system memory also 1GB is available there, it would have higher > latency though). > > It is perfectly viable to build Sparc v7 or v8 32bit binaries in a > chroot on a fast machine also, and I would recommend this if you wish > to retain sanity rather than attempting cross compiler voodoo, unless > that is your thing. It is, sadly, my thing. The above 250 line bash script builds: aarch64 armv7l i686 mips powerpc s390x x86_64 armv4l armv7m m68k mips64 powerpc64 sh2eb armv5l i486 microblaze mipsel powerpc64le sh4 That's toybox booting to a shell prompt and a linux kernel configured for qemu for each target. Adding new targets looks something like: elif [ "$TARGET" == m68k ]; then QEMU="m68k -M q800" KARCH=m68k KARGS=ttyS0 VMLINUX=vmlinux KCONF=MMU,M68040,M68KFPU_EMU,MAC,SCSI_MAC_ESP,MACINTOSH_DRIVERS,ADB,ADB_MACII,NET_CORE,MACSONIC,SERIAL_PMACZILOG,SERIAL_PMACZILOG_TTYS,SERIAL_PMACZILOG_CONSOLE elif [ "$TARGET" = s390x ]; then QEMU="s390x" KARCH=s390 VMLINUX=arch/s390/boot/bzImage KCONF=MARCH_Z900,PACK_STACK,NET_CORE,VIRTIO_NET,VIRTIO_BLK,SCLP_TTY,SCLP_CONSOLE,SCLP_VT220_TTY,SCLP_VT220_CONSOLE,S390_GUEST (Well, modulo thunderbird being unable to an indent a line that goes off the right edge of the screen. The mozilla foundation somehow managed to spend half a billion dollars in 2019 but it wasn't on thunderbird, I can tell you that.) Anyway, I wrote a couple FAQ entries trying to explain the worst of it: https://landley.net/toybox/faq.html#cross https://landley.net/toybox/faq.html#mkroot > Anyways it could be that people that want this get around to fixing > SILO eventually and just sit on this last kernel version... *shrugs* They're never sitting on the _last_ kernel version. They're generally way back from there. Been true forever off of x86 (and now arm): https://lore.kernel.org/lkml/201002211025.11588.rob@xxxxxxxxxxx/T/ > Chase Rob
