x86 setup: be more verbose when probing EDD

On early boot, probing the Bios for EDD happens without any message.

Enhanced Disk Drive Services (EDD) is a mechanism to match x86 BIOS device
names (int13 device 80h) to Linux device names (e.g. /dev/sda, /dev/hda)

There are buggy Bios out there having problems with EDD. This can be problems
with the Bios itself or with addon cards, too.

This patch is adds an informational message on early boot.

CONFIG_EDD is not set with defconfig, but with allmodconfig (i.e. CONFIG_EDD=m)
so the EDD probe may be active on early boot on many systems nowadays.

I can tell, that the probe is active on SuSE distro and with that I have seen
more than one system hanging endlessly with those "black screen with a blinking
cursor in the the upper left" on installation, making it difficult for the end-
user to find out, what`s the issue.
For sure I have seen this on FujitsuSiemens PCs with i810 and with i815 chipset.

This one also honours the "quiet" bootparam.

Also see:
http://marc.info/?l=linux-kernel&m=119781937207969&w=2
http://marc.info/?l=linux-kernel&m=119783934032326&w=2
http://marc.info/?l=linux-kernel&m=119783678529100&w=2

Signed-off-by: Roland Kletzing <devzero@web.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/boot/edd.c b/arch/x86/boot/edd.c
index bd138e442ec25bfd08b5dec3a166d1f5d4e6a48e..b3504cb24de72133bc364a9f46bf69d008f6d989 100644 (file)
--- a/arch/x86/boot/edd.c
+++ b/arch/x86/boot/edd.c
@@ -129,6 +129,7 @@ void query_edd(void)
        char eddarg[8];
        int do_mbr = 1;
        int do_edd = 1;
+       int be_quiet;
        int devno;
        struct edd_info ei, *edp;
        u32 *mbrptr;
@@ -140,12 +141,21 @@ void query_edd(void)
                        do_edd = 0;
        }
 
+       be_quiet = cmdline_find_option_bool("quiet");
+
        edp    = boot_params.eddbuf;
        mbrptr = boot_params.edd_mbr_sig_buffer;
 
        if (!do_edd)
                return;
 
+       /* Bugs in OnBoard or AddOnCards Bios may hang the EDD probe,
+        * so give a hint if this happens.
+        */
+
+       if (!be_quiet)
+               printf("Probing EDD...");
+
        for (devno = 0x80; devno < 0x80+EDD_MBR_SIG_MAX; devno++) {
                /*
                 * Scan the BIOS-supported hard disks and query EDD
@@ -162,6 +172,9 @@ void query_edd(void)
                if (do_mbr && !read_mbr_sig(devno, &ei, mbrptr++))
                        boot_params.edd_mbr_sig_buf_entries = devno-0x80+1;
        }
+
+       if (!be_quiet)
+               printf("OK\n");
 }
 
 #endif