Date: Thu, 26 Nov 2020 01:32:09 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 251389] linuxkpi malloc is not strictly compatible with Linux Message-ID: <bug-251389-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D251389 Bug ID: 251389 Summary: linuxkpi malloc is not strictly compatible with Linux Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: jhibbits@FreeBSD.org Linux's kmalloc seems to provide the following guarantees: * GPF_KERNEL returns memory in the lower 4GB physical space * Allocations are physically contiguous malloc(9) does not make either of these guarantees. This ends up breaking = DRM modules on powerpc64 platforms, where even if memory happens to be contiguo= us it may not be in the bottom 4GB physical address space, and it may even be = in a different NUMA domain, where NUMA domains are physically indexed at 1<<45, = such that the bottom 4GB of the second NUMA domain doesn't fit into the 40-bit PA range accessible to Radeon GPUs. Contiguity can be emulated with contigmalloc(9), but that's not a viable solution for replacing all calls, as it's very possible for the size to not= be known and traceable through the lifetime of a pointer. --=20 You are receiving this mail because: You are the assignee for the bug.=
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