Re: CVS commit: src/sys/arch/atari/stand/installboot

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

christos@ wrote:

> On Nov 14,  3:00am, tsutsui%ceres.dti.ne.jp@localhost (Izumi Tsutsui) wrote:

> | "Test it (or call for testers) before commit"
> | because installboot could be fatal on install floppy and bootstrap.
> | 
> | > but memcpy is the only way.
> | 
> | - cast via (void *)
> 
> That does not work.
> 
> | - union {uint16_t w[256]; struct bootblock bbp;}
> 
> That works...

How about this one? (cksum seems updated properly on the real machine)

--- installboot/installboot.c	2014-11-14 13:21:10.000000000 +0900
+++ installboot/installboot.c	2014-11-14 23:03:28.000000000 +0900
@@ -467,7 +467,10 @@
     struct disklabel *label, u_int magic)
 {
 	int		 fd;
-	uint16_t	 sum;
+	union {
+		struct bootblock *bbp;
+		uint16_t *word;		/* to fill cksum word */
+	} bbsec;
 
 	memset(bb, 0, sizeof(*bb));
 
@@ -499,10 +502,9 @@
 	setIDEpar(bb->bb_xxboot, sizeof(bb->bb_xxboot));
 
 	/* set AHDI checksum */
-	sum = 0;
-	memcpy(bb->bb_xxboot + 255 * sizeof(sum), &sum, sizeof(sum));
-	sum = 0x1234 - abcksum(bb->bb_xxboot);
-	memcpy(bb->bb_xxboot + 255 * sizeof(sum), &sum, sizeof(sum));
+	bbsec.bbp = bb;
+	bbsec.word[255] = 0;
+	bbsec.word[255] = 0x1234 - abcksum(bb->bb_xxboot);
 
 	if (verbose) {
 		printf("Primary   boot loader: %s\n", xxb);

---
Izumi Tsutsui