[Bug 279901] glibc-2.39-2 and above on the host segfault

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=279901

--- Comment #65 from Koichiro Iwao <meta@FreeBSD.org> ---
(In reply to Florian Weimer from comment #63)

Let me sort out the remaining issues. 

1TB L3 cache issue:
- Addressed in glibc upstream
  - AlmaLinux 9.5 and Kitten 10 already include the upstream patch
- Addressed also on bhyve side (temporary patch)

However, the temporary bhyve patch broke glibc on AlmaLinux 8 / EL8
(glibc-2.28-251.el8_10.13). So the temporary patch for bhyve might have
regression. This regression prevents the bhyve patch from being merged. 

The bhyve patch means here is the following:

--- a/sys/amd64/vmm/x86.c
+++ b/sys/amd64/vmm/x86.c
@@ -152,6 +152,8 @@ x86_emulate_cpuid(struct vcpu *vcpu, uint64_t *rax,
uint64_t *rbx,
                                 * pkg_id_shift and other OSes may rely on it.
                                 */
                                width = MIN(0xF, log2(threads * cores));
+                               if (width < 0x4)
+                                       width = 0;
                                logical_cpus = MIN(0xFF, threads * cores - 1);
                                regs[2] = (width << AMDID_COREID_SIZE_SHIFT) |
logical_cpus;

To reproduce the EL8 glibc issue, run the following command on PATCHED bhyve
environment.

$ podman run -it --rm quay.io/almalinuxorg/almalinux:8 /bin/bash
$ podman run -it --rm quay.io/rockylinux/rockylinux:8 /bin/bash

AlmaLinux doesn't have a8 branch for glibc package, so there are no
AlmaLinux-specific patches. AlmaLinux's glibc and Rocky Linux's one are built
from the same source. 

So what we need to do is, 
- Improve bhyve patch not to break EL8 glibc but fix EL9 glibc issue (1TB L3
cache issue)
- Fix EL8 glibc issue in upstream if it is an upstream issue

I will give you access for PATCHED bhyve environment if necessary. Send me your
SSH public key.

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