From: Konrad Rzeszutek Wilk Date: Tue, 26 Jan 2016 21:30:58 +0000 (-0500) Subject: libxc/xc_domain_resume: Update comment. X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=882c0b009bf81e94b9a03594351297bdeb0ff0fb;p=people%2Fliuw%2Flibxenctrl-split%2Fxen.git libxc/xc_domain_resume: Update comment. To hopefully clarify what it meant. Also point out that mechanism by which the return 1 value is done is via an intimate knowledge of the hypercall ABI (i.e. which register - eax - is the return value). Signed-off-by: Konrad Rzeszutek Wilk Acked-by: Wei Liu --- diff --git a/tools/libxc/xc_resume.c b/tools/libxc/xc_resume.c index 87d43242ef..e692b810f7 100644 --- a/tools/libxc/xc_resume.c +++ b/tools/libxc/xc_resume.c @@ -248,11 +248,20 @@ out: /* * Resume execution of a domain after suspend shutdown. * This can happen in one of two ways: - * 1. Resume with special return code. - * 2. Reset guest environment so it believes it is resumed in a new - * domain context. + * 1. (fast=1) Resume the guest without resetting the domain environment. + * The guests's call to SCHEDOP_shutdown(SHUTDOWN_suspend) will return 1. + * + * 2. (fast=0) Reset guest environment so it believes it is resumed in a new + * domain context. The guests's call to SCHEDOP_shutdown(SHUTDOWN_suspend) + * will return 0. + * + * (1) should only by used for guests which can handle the special return + * code. Also note that the insertion of the return code is quite interesting + * and that the guest MUST be paused - otherwise we would be corrupting + * the guest vCPU state. + * * (2) should be used only for guests which cannot handle the special - * new return code. (1) is always safe (but slower). + * new return code - and it is always safe (but slower). */ int xc_domain_resume(xc_interface *xch, uint32_t domid, int fast) {