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authorChristian Krinitsin <mail@krinitsin.com>2025-06-30 12:24:58 +0000
committerChristian Krinitsin <mail@krinitsin.com>2025-06-30 12:27:06 +0000
commit33606b41d35115f887ea688b1a16f2ff85bf2fe4 (patch)
tree406b2c7b19a087ba437c68f3dbf0b589fa1d6150 /results/scraper/launchpad-without-comments/1904317
parentadedf8771bc4de3113041ca21bd4d0d1c0014b6a (diff)
downloadqemu-analysis-33606b41d35115f887ea688b1a16f2ff85bf2fe4.tar.gz
qemu-analysis-33606b41d35115f887ea688b1a16f2ff85bf2fe4.zip
add launchpad bug reports without comments
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+cpu feature selection is not affected to guest 's cpuid with whpx
+
+On windows with -accel whpx, "-cpu" is ignored without any messages.
+Guest recognizes features as same as host's.
+
+Confirmed on v5.2.0-rc1.
+
+I suggest qemu may do,
+
+- Warn with incompatible -cpu options were given.
+- Enhance cpuid handling.
+
+Background:
+I was investigated mmio and block copy issue in Linux kernel.
+I met a problem that Linux went ill for touching mmio with whpx. (not with tcg)
+I suspect erms(enhanced rep movs) might trigger.
+I tried to mask erms on qemu with -feature,erms, but it was ineffective.
+
+At last, I disabled erms manually, to tweak whpx-all.c to mask erms in cpuid.
+
+FYI, qemu with whpx from/to mmio, "rep movsb" does byte access regardless of erms.
+Linux kernel tends to choose not "rep movsq" but "rep movsb" with erms.
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