RFR: 8264412: AArch64: CPU description should refer DMI
Andrew Haley
aph at openjdk.java.net
Tue Mar 30 16:23:26 UTC 2021
On Tue, 30 Mar 2021 07:53:59 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:
> `jdk.CPUInformation` event on AArch64 has valid CPU description in [JDK-8262491](https://bugs.openjdk.java.net/browse/JDK-8262491), however it does not work on UEFI booted machine.
>
> [JDK-8262491](https://bugs.openjdk.java.net/browse/JDK-8262491) refers device tree to get board name, however it does not exist on UEFI. We need to refer DMI.
> However we need to have root privilege, so we refer /sys/devices/virtual/dmi/id to avoid it.
>
> We can get board name from /sys/devices/virtual/dmi/id/board_name, but some machine set empty string to it. So we will refer /sys/devices/virtual/dmi/id/product_name as a fallback.
>
> For example, we can get following CPU description on AWS A1 instance after this change:
>
> jdk.CPUInformation {
> startTime = 05:28:24.506
> cpu = "AArch64"
> description = "AArch64 a1.2xlarge 0x41:0x0:0xd08:3, simd, crc, aes, sha1, sha256"
> sockets = 8
> cores = 8
> hwThreads = 8
> }
This patch is basically OK, except the question about a somewhat obscure bit of code.
src/hotspot/os_cpu/linux_aarch64/vm_version_linux_aarch64.cpp line 178:
> 176: ssize_t read_sz = read(fd, buf, buflen - 1);
> 177: close(fd);
> 178: if ((read_sz > 0) && isgraph(*buf)) {
What is `isgraph(*buf)` doing here? Is the problem that the file might contain binary data?
-------------
PR: https://git.openjdk.java.net/jdk/pull/3259
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