From 02dea0875b0f9b331a65fd6097dfd6115ca4ef24 Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Fri, 31 Mar 2006 02:30:08 -0800 Subject: [PATCH] UML: Hotplug memory, take 2 Changes since first version added check for MADV_REMOVE support on the host fixed error return botch shrunk sprintf array by one character This adds hotplug memory support to UML. The mconsole syntax is config mem=[+-]n[KMG] In other words, add or subtract some number of kilobytes, megabytes, or gigabytes. Unplugged pages are allocated and then madvise(MADV_TRUNCATE), which is a currently experimental madvise extension. These pages are tracked so they can be plugged back in later if the admin decides to give them back. The first page to be unplugged is used to keep track of about 4M of other pages. A list_head is the first thing on this page. The rest is filled with addresses of other unplugged pages. This first page is not madvised, obviously. When this page is filled, the next page is used in a similar way and linked onto a list with the first page. Etc. This whole process reverses when pages are plugged back in. When a tracking page no longer tracks any unplugged pages, then it is next in line for plugging, which is done by freeing pages back to the kernel. Signed-off-by: Jeff Dike Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/os-Linux/start_up.c | 20 -------------------- 1 file changed, 20 deletions(-) (limited to 'arch/um/os-Linux/start_up.c') diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c index 32753131f8d8..387e26af301a 100644 --- a/arch/um/os-Linux/start_up.c +++ b/arch/um/os-Linux/start_up.c @@ -470,25 +470,6 @@ int can_do_skas(void) } #endif -int have_devanon = 0; - -/* Runs on boot kernel stack - already safe to use printk. */ - -void check_devanon(void) -{ - int fd; - - printk("Checking for /dev/anon on the host..."); - fd = open("/dev/anon", O_RDWR); - if(fd < 0){ - printk("Not available (open failed with errno %d)\n", errno); - return; - } - - printk("OK\n"); - have_devanon = 1; -} - int __init parse_iomem(char *str, int *add) { struct iomem_region *new; @@ -664,6 +645,5 @@ void os_check_bugs(void) { check_ptrace(); check_sigio(); - check_devanon(); } -- cgit v1.2.2