handle flashy validation for yosemite5a7/AST2700

Summary:
Currently any attempt to run oobgrader against a ysoemite5a7 device is failing as it cannot verify the image in flashy checks and remediations

Let's add a fix to the whole image for the U-Boot version string (step 40) and adding the a7's 4088 KB manifest offset to the candidate list (step 41)

Test Plan:
```
$oobgrader --host rtptest6715-oob.snc8.facebook.com --fbpkg-tag openbmc.image.yosemite5a7:v2026.27.1 --flashy-tag 5d49d87 --wait
```
Created job: https://fburl.com/scuba/openbmc_upgrades/b81b19sc

BMC successfully upgraded:
```
$ ssh root@rtptest6715-oob.snc8.facebook.com
Last login: Mon Jul 27 12:11:30 2026 from 2401:db00:eef0:1120:3520:0:a804:7c6
root@bmc:~# cat /etc/issue
OpenBMC Release yosemite5a7-v2026.27.1

```

Reviewed By: amithash, ryazwinski, williamspatrick

Differential Revision: D112993974

fbshipit-source-id: cba093b85dcef6961ed8bafe4528846e9f27c87f

Author: cjcon90

tools/flashy/lib/validate/compatibility.go

@@ -115,9 +115,13 @@ var getNormalizedBuildNameFromVersion = func(ver string) (string, error) {
 // WARNING: This relies on the U-Boot version string on the image
 // there is no guarantee that this will succeed
 var GetOpenBMCVersionFromImageFile = func(imageFilePath string) (string, error) {
-	// mmap the first 1MB of the image file
-	imageFileBuf, err := fileutils.MmapFileRange(
-		imageFilePath, 0, 1024*1024, syscall.PROT_READ, syscall.MAP_SHARED,
+	// mmap the whole image file. The U-Boot version string is near the start of
+	// flat images, but for container-packaged images (e.g. AST2700/yosemite5a7,
+	// where U-Boot lives inside a multi-MB u-boot-fit partition) it sits several
+	// MB in, past any fixed-size window. The regex scan stops at the first match,
+	// so only the pages up to the match are faulted in.
+	imageFileBuf, err := fileutils.MmapFile(
+		imageFilePath, syscall.PROT_READ, syscall.MAP_SHARED,
 	)
 	if err != nil {
 		return "", fmt.Errorf("Unable to read and mmap image file '%v': %v",

tools/flashy/lib/validate/compatibility_test.go

@@ -196,11 +196,11 @@ func TestGetNormalizedBuildNameFromVersion(t *testing.T) {
 }
 
 func TestGetOpenBMCVersionFromImageFile(t *testing.T) {
-	// mock and defer restore MmapFileRO
-	mmapOrig := fileutils.MmapFileRange
+	// mock and defer restore MmapFile
+	mmapOrig := fileutils.MmapFile
 	munmapOrig := fileutils.Munmap
 	defer func() {
-		fileutils.MmapFileRange = mmapOrig
+		fileutils.MmapFile = mmapOrig
 		fileutils.Munmap = munmapOrig
 	}()
 
@@ -247,7 +247,7 @@ func TestGetOpenBMCVersionFromImageFile(t *testing.T) {
 	}
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
-			fileutils.MmapFileRange = func(filename string, offset int64, length, prot, flags int) ([]byte, error) {
+			fileutils.MmapFile = func(filename string, prot, flags int) ([]byte, error) {
 				if filename != "x" {
 					t.Errorf("want filename '%v' got '%v'", "x", filename)
 				}

tools/flashy/lib/validate/partition/p_lfmeta.go

@@ -19,8 +19,9 @@ type LFMetaLocations struct {
 //
 //	https://github.com/openbmc/openbmc/blob/2d43f028cd98e622d53365b83c39cd120cac5cc2/meta-phosphor/classes/image_types_phosphor.bbclass#L58
 var lfmetaImageMetaLocations = []LFMetaLocations{
-	{380 * 1024, 4 * 1024}, // default 32 MB layout
-	{888 * 1024, 8 * 1024}, // default 64 MB and 128 MB layout
+	{380 * 1024, 4 * 1024},  // default 32 MB layout
+	{888 * 1024, 8 * 1024},  // default 64 MB and 128 MB layout
+	{4088 * 1024, 8 * 1024}, // AST2700 (e.g. yosemite5a7): manifest precedes the 4 MB u-boot region
 }
 
 func init() {