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Re: [PATCH v1 4/5] util: add qemu_get_host_physmem utility function
From: |
BALATON Zoltan |
Subject: |
Re: [PATCH v1 4/5] util: add qemu_get_host_physmem utility function |
Date: |
Fri, 17 Jul 2020 15:32:07 +0200 (CEST) |
User-agent: |
Alpine 2.22 (BSF 395 2020-01-19) |
On Fri, 17 Jul 2020, Alex Bennée wrote:
This will be used in a future patch. For POSIX systems _SC_PHYS_PAGES
isn't standardised but at least appears in the man pages for
Open/FreeBSD. The result is advisory so any users of it shouldn't just
fail if we can't work it out.
The win32 stub currently returns 0 until someone with a Windows system
can develop and test a patch.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Cc: BALATON Zoltan <balaton@eik.bme.hu>
Cc: Christian Ehrhardt <christian.ehrhardt@canonical.com>
---
include/qemu/osdep.h | 10 ++++++++++
util/oslib-posix.c | 11 +++++++++++
util/oslib-win32.c | 6 ++++++
3 files changed, 27 insertions(+)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 4841b5c6b5f..7ff209983e2 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -665,4 +665,14 @@ static inline void qemu_reset_optind(void)
*/
char *qemu_get_host_name(Error **errp);
+/**
+ * qemu_get_host_physmem:
+ *
+ * Operating system agnostiv way of querying host memory.
Typo: agnostiv -> agnostic
+ *
+ * Returns amount of physical memory on the system. This is purely
+ * advisery and may return 0 if we can't work it out.
+ */
+size_t qemu_get_host_physmem(void);
+
#endif
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 36bf8593f8c..d9da782b896 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -839,3 +839,14 @@ char *qemu_get_host_name(Error **errp)
return g_steal_pointer(&hostname);
}
+
+size_t qemu_get_host_physmem(void)
+{
+#ifdef _SC_PHYS_PAGES
+ long pages = sysconf(_SC_PHYS_PAGES);
+ if (pages > 0) {
+ return pages * qemu_real_host_page_size;
The Linux man page warns that this product may overflow so maybe you could
return pages here.
+ }
+#endif
+ return 0;
+}
diff --git a/util/oslib-win32.c b/util/oslib-win32.c
index 7eedbe5859a..31030463cc9 100644
--- a/util/oslib-win32.c
+++ b/util/oslib-win32.c
@@ -828,3 +828,9 @@ char *qemu_get_host_name(Error **errp)
return g_utf16_to_utf8(tmp, size, NULL, NULL, NULL);
}
+
+size_t qemu_get_host_physmem(void)
+{
+ /* currently unimplemented */
+ return 0;
+}
For Windows this may help:
https://stackoverflow.com/questions/5553665/get-ram-system-size
not sure about other OSes.
Regards,
BALATON Zoltan
[PATCH v1 5/5] accel/tcg: better handle memory constrained systems, Alex Bennée, 2020/07/17